If you perform moderation actions on threads via the forum display they don't show up in the thread notes in the moderation options at the bottom of a thread. I can see why though now, it doesn't store the TIDs as it could be multiple threads you're performing the action on. Might suggest a change to it though.
Ahaha no wonder we didn't know who had unapproved what :p
Seems pretty close to a BUG!