Hi,
We also experience the same behaviour. There are more than 6 groups and their users assigned to the server, but after adflush -f only users of this 1 group are mssing.
When I do adquer user |grep xyz it returns empty, or when I do id xyz, it says there are no such a user.
If I do adquery user xyz it finds the user and displays user information, ad all commands start to work for a while.
This only happens on 1 group. Did you find any solution?