SSL Visibility ( 4.8.x or lower) being managed by Management Center (3.2.x or lower)
Admin recently set Maximum Concurrent Logins Per User to 1 (one) in SSL visibility. This would cause a log out of a previous user session that uses the same credentials.
Note: By default, Management Center collects information (health checks) from all activated manage devices every 10 seconds. This setting is globally configured.
Temporarily deactivate said SSL Visibility on Management Center.
MC UI > Network > Right click on SSL Visibility device in question > "Change Monitoring Status" > Choose "Deactivate Devices" > Run Now
This should free up the session that would give "admin" ability to manage SSL Visibility via browser to change necessary settings.
Note: To continue monitoring said SSL Visibility in Management Center, you will need to Reactivate (Activate) it back in Management Center once the issue is corrected.