I had a similar issue with Qlikview many years ago. One day, users came in and saw that their custom objects had up and left the building. We searched for them, but couldn't find them. We assumed that the folks in the Identity Management department in Germany had fiddled with Active Directory, but we never go to the bottom of it.
I thought Bookmarks were stored in the Postgres db, but that's a hunch, not actual knowledge.
Some times I feel sorry to say, why Qlik doesn't share these things are Knowledge base articles like all others tools
Sorry If I bother you but this is a fact in both QlikView and QlikSense that people suffer at times with things in the server part like missing CALs , loosing Bookmarks, loosing custom objects etc.
My sincere suggestion to Qlik Knowledge base would be in this real competitive world where you are facing health competition with other tools , please increase your help base , video base and knowledge base