If Reports Sharing does not work after you upgraded to FUJI
After FUJI upgrade you may discover that Reports shared by your users with groups and other users suddenly become not available to those with whom they had shared them.
The issue is coming from a Read ACL over sys_report table which should check report availability for Groups and Users using sys_report_users_groups table. But it checks the security using legacy fields located in sys_report record itself.
To fix the issue simply activate the plug-in com.glideapp.report_security (aka “Report Security – enforce access control checks”). It updates the Read ACL over sys_report.
Important to mention that this plug-in is already activated in new servicenow instances but in old instances upgrading to FUJI it is NOT activated by default.
Hope this helps to upgrade your instances smoothly to Fuji!