MUKATIM1 Please check Operator disablement policy time with Admin user in the Security Policies as it might be having very less time for the operators. If you can not login with any user try logging in Operator table and check that flag.
Another reason could be because of your Authentication methods like SSO it may be getting set to that option at runtime. If you face this issue for all other users just check if that option in Operator ID is enabled for other operators always or just changing while that user logs in.
I don't think this issue could be because of PEGA upgrade so if you can not get rid of anyway please clear the operator disable option from DB.