Access CRM Plug-in for Outlook 2.7.6 makes Outlook flash

Office 365 v2302, is unfortunately too new and likely introducing changes that are causing the issue. The Outlook plugin (OPI), requires the semi-annual update channel (see side note #1 in "Plug-ins Supported Platforms" below). As of this moment, that would be "Semi-Annual Enterprise Channel v2202 or v2208". Try changing the update channel to one of those semi-annual versions and see if that resolves the issue. If you are still experiencing issues after changing over, feel free to open a Support Case with us, so we can perform some additional troubleshooting.

Plug-ins Supported Platforms:
https://support.sugarcrm.com/Resources/Supported_Platforms/Plug-ins_Supported_Platforms/

An overview of each update channel for Office 365 can be found here:
https://learn.microsoft.com/en-us/deployoffice/updates/overview-update-channels#semi-annual-enterprise-channel-overview

Each of the update channels can be viewed here along with additional information about each one;
https://learn.microsoft.com/en-us/officeupdates/update-history-microsoft365-apps-by-date

Details on changing the Office 365 update channel can be found here and can be performed by your Office 365 admin or IT team: 
https://learn.microsoft.com/en-us/deployoffice/updates/change-update-channels