We were not aware about it until client mentioned that they are not able to see groups to assigned.
I am an administrator and i didn't find that in the list. But when i went into database, in permission groups i can see these groups but not on UI to assigned to given users
@manish.joisar A good rule - always check if you are using the latest release, if not, then make a backup and upgrade to see if that fixes your issue. Also read through the release notes between the version you are running and the newest release.