In Salesforce Summer '24 - SuMo Gallery Images with the "Adopt Updated Content Security Policy (CSP)" Release Update enabled – If the Salesforce Release Update "Adopt Updated Content Security Policy (CSP) Directives" is enabled, the SuMo Gallery images will not display.
Salesforce aren't enabling the update by default, and it isn't due to be enforced until Winter 25.

For further details, see this Salesforce Help Article.

Competition Assistant in Spring '24, SuMo 8.56 – In the previous SuMo version, i.e. 8.56, the Competition Assistant doesn't work in Spring '24 due to a Salesforce Known Issue.
The workaround is to upgrade SuMo to version 8.59 or disable the Salesforce session setting "Use Lightning Web Security for Lightning Web Components and Aura Components".
As of 01/02/2024, the solution for the Known Issue has been scheduled.
See the Known Issue for details: [Spring'24]When loading an Aura component having jQuery ,it gives error draggable, droppable is not a function /[Unexpected token '(']

Duplicate Observation records due to Salesforce's handling of triggers for the Lead object
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Insight: slow network connections – When the Insights Lightning page is loaded on a PC that has a slow network connection or has browser caching disabled, warning messages may be displayed if the viewing user's language is not set to English. In this instance, users should close the messages that are displayed and wait for the page to complete loading.

Insight Detail Component – The "Show Charts" component property in the Lightning App Builder displays/hides all of the individual charts whose own properties are currently set to display those charts. The "Show Charts" property, therefore, does not control the state of the three individual chart properties.

Inspire Channel Launch – When using the "Launch Inspire" tab in Lightning Experience the Channel will start in a new tab. This behaviour is different from the Classic Salesforce UI where the Channel is launched within the same tab.
See the "Logout Session Timeout Setting with Inspire" information in the Implementation Guidance section for the relevance of leaving multiple tabs logged in when displaying an Inspire Channel on a TV display.

Gallery Scrollbars – When accessing the Gallery, multiple scroll bars may be displayed for vertical scrolling. This does not prevent the user from scrolling vertically down the page when required.

Inspire voting - Motivation Designer permissions – Currently, a Motivation Designer with the Salesforce "Standard User" profile cannot enable/disable Inspire Voting. This is because the permission set only has "Read" access to "Polls" object.
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If those Users need the full Inspire Voting functionality, the Motivation Designer (Supplementary) permission set needs the following additional permissions for the Polls object:
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Edit, Delete, View All and Modify All

Orgs with "audit fields editable on creation" enabled – Creating or cloning Graphics records is affected in Orgs where this setting has been enabled, where audit fields are writable when you first create a record; when creating a Graphic record, Salesforce validation requires values in the Last Modified Date and Created By fields. To get around this, you can remove the Last Modified Date and Created By fields from that field set. See this Salesforce article for info on this setting: https://help.salesforce.com/apex/htviewsolution?id=000213290&language=en_US

Competition Email Notifications – If any Competitions have notifications enabled, users may experience delays in receiving Start or End notifications via Email, in that Emails may not be received exactly prior to the competition Start/End date and time - specifically if the set times are in the near future.
This is due to resource availability on the Salesforce platform and the time delay involved when processing emails across multiple Internet Service Providers. Therefore, we advise to set up competition notifications significantly far enough into the future to ensure that Start and End notifications will be processed in a timely manner.

Behaviours based on deleted objects – It is recommended that if a custom Object is to be deleted from an org, any Behaviours that had been created based on that Object are also deleted. Once an Object has been deleted, Motivation Designers will be able to view the Behaviour record by clicking on its name in the list views; however, if they were to click on the "Edit" link an error message would be displayed. Therefore, it is advised that Motivation Designers view the Behaviour record and then click on the "Delete" button on the view page to delete it.

Opportunity Splits – For Orgs in which Opportunity Splits are enabled, there is a known issue related to Opportunity rewarding; for Behaviours with criteria based on the value of the "Amount" field, the Recipient is not rewarded correctly when an Opportunity is edited so that the Amount value meets the criteria. However, this is not a problem when a new Opportunity is added that meets the Amount value criteria.

Routines that generate Chatter Posts – When setting up a Salesforce routine - through processes, flows, etc - that will automatically send a Chatter Post when a reward record is created, it is important to ensure that the resulting Chatter Notification doesn't also qualify for assessment and reward as this may cause an infinite reward generation loop. To ensure this doesn't happen, the Motivation Designer should include relevant criteria in the Chatter-related Behaviour(s).

Salesforce Shield and Scheduled Behaviours – Fields that have been encrypted using Salesforce Shield (Platform Encryption) are not accessible in SOQL and cannot be used in query filter clauses (e.g. WHERE or ORDER). Therefore, Scheduled Base Behaviours (based on any object, including "Metric") cannot be used if they contain Behaviour Criteria that reference encrypted fields.

Rewarding when the linked Parent object record is edited – When Behaviour Criteria reference parent object fields, Rewards will not be generated if the parent object record is changed on the child object record that the Base Behaviour is configured for, even if the Behaviour Criteria is met.
For example, using the criteria "Opportunity.Amount > 5000 AND Opportunity.Account.AnnualRevenue > 10000" will result in a Reward being generated for an Opportunity that is linked to an Account that has an "Annual Revenue" greater than "10000" if the Opportunity's "Amount" field value is changed to over "5000".
However, a Reward will not be generated if the Account linked to the Opportunity is edited to one with over "10000" Annual Revenue.
The workaround to support this is to set the Base Behaviour "Action" to "Every time a record is created or edited" and ensure that the "Multiple rewards" option is not checked.

Aggregate Behaviours with a Wait Time – When viewing an Opportunity record, Nudges for Opportunity-related Behaviours are hidden from the Player during the Wait Time, as the behaviour isn't actually available at that point. However, a problem has been identified where Nudges for Aggregate Task/Event behaviours with a Wait Time are always displayed to the Player on the Opportunity record while the Behaviour is "In Progress", regardless of whether the Behaviour is available or not.

Behaviour Nudges and Spectators – A Spectator in a Competition or Experience Group may not see Behaviour Nudges on Task/Event records, even if the Behaviour's criteria have not been met.

Inspire Occasional Channel "whiteout" on launch or reload – In rare circumstances, the Inspire page will display a white screen either at the time the Channel is launched or when it is reloaded.
This is an intermittent problem and the reasons for it are currently unknown. Should this occur the remedy is to simply reload the page using the browser's "Refresh" function. It should be noted that a running Inspire screen is automatically reloaded every 10 hours; therefore, it's possible to see this issue even after the Inspire page has been running for an extended period of time.

Inspire Content based on Knowledge Articles – In order for Knowledge Articles to be configured for display on Leaderboards within Channel Builder, filter conditions must be added for "Language" and "Publication Status" before any fields are placed on the canvas. Also, note that additional system permission may be required to select Articles with a "Publication Status" equal to Draft. In addition, multiple filter values cannot be used for the Language and Publication Status fields, else a message will be displayed. These are underlying restrictions required by salesforce.com.

Display of fields in Field Selector – When accessing the Field Selector within Base Behaviours using a web browser at a resolution of 1280 x 800, the list of fields may not be displayed in the last panel until the user scrolls up or down within the panel.

Opportunity Insight with Salesforce Platform Encryption enabled – When the Opportunity Name field is encrypted via Salesforce Platform Encryption, a Salesforce error will be displayed when sorting the Opportunity Insight list by name (i.e. "field "Name" can not be sorted in a query call").
This is because Salesforce encrypted fields cannot be used in certain SOQL queries.
See the Salesforce article General Shield Platform Encryption Considerations for full details.

Inspire board and Channel Builder with Salesforce Platform Encryption enabled – When Salesforce Platform Encryption is enabled, the Inspire screen will not display any table at all if any of the encrypted fields are included in a Leaderboard.
Also, an error will display in the Channel Builder when attempting to edit a Leaderboard that includes an encrypted field.
See the Salesforce article General Shield Platform Encryption Considerations for full details.

Performance History Chart – Week number calculation - Currently, the week number calculation starts Week 1 on 1st January, which means that a couple of days at the end of the year may be displayed in Performance Charts as "Week 53".
In 2014, for example, 1st January was a Wednesday so Week 1 started on a Wednesday and ended on a Tuesday.
Therefore, data created on the 29th, 30th or 31st December 2014 will have appeared on the Performance History chart as "W53".

Salesforce Session Setting "Cross-Origin Embedder Policy (COEP)" – If the COEP option is enabled in the Org, there are Graphics problems in the Player and Motivation Designer UIs, in Lightning and Classic.

Clickjack protection for Visualforce pages – Sumo summary components (as used in the sidebar and the home page) will not be displayed correctly if the option "Clickjack protection for customer Visualforce pages with headers disabled" has been enabled. Either ensure that this option has not been enabled or do not deploy the sidebar summary components.

Competition sidebar component - This component may not display if "special characters", e.g. double quotes, are included in the name of the Competition or Experience Group. We recommend avoiding special characters in Competition and Experience Group names.

Salesforce Session Setting "Cross-Origin Embedder Policy (COEP)" – If the COEP option is enabled in the Org, there are a few Graphics problems in the Player UI in Classic, i.e:

Safari - Classic Rewards, Behaviours and Predictions Visualforce components – In some instances a Maximum Redirects Exceeded message will be displayed. We recommend using another browser, preferably Google Chrome.

Microsoft Edge and SVG images – SVG images may not load correctly in some areas of the app. The images will display OK after refreshing the browser.

Display of Leaderboard – The Sumo Leaderboard when displayed on mobile is currently rendering some of the user ranks (from rank number 6) underneath subsequent components on the Performance Centre page.

Display of Icons – Icons that have been uploaded onto Graphics Records are not being correctly displayed on Mobile within Sumo components.