I have a reoccurring problem with my hidden mailboxes. They will appear in the GAL out of the blue. I go in and check that they are still hidden and the checkbox still shows as selected. I even have checked the object in ADSIedit and it is also set to be hidden there. I can unhide and re-hide the mailbox, but this has become a pain to do all the time. I am using Exchange Server 2010 SP3 rollup 6 on 3 servers. I originally had them setup in a DAG with several copies, but this still happens, if I remove the copies of the database from the other servers. All three servers are setup to run all roles, but all clients point at one server and the others are used for failover and backup purposes.
My AD is setup with two domain controllers and only one is the GC. I have my infrastructure master on the DC that is not the GC as well.
I have looked in the forums and do not see anyone else reporting this issue. I have tried everything I can think of and would appreciate any help I can get in this matter.