SharePoint groups started to disappear- totally randomly, within a single site collection. I am pretty sure they are not deleted because we have few site collection admins with knowledge.
Site A has members, owners and visitors group. we realized that owners and visitors have been removed. The groups are vanished from People and Groups as well!
On the other instance, Site B,all groups have been removed / vanished and an individual person name was added to permissions. I am so confused.how can I trace what might be happening?