but they -do- show up in your post history, that means the thread is broken.
I've written a repair tool for staff
to fix this issue (it's a staff thread, I link it to make it easier to find >_>). Just PM a staff member with a link to the problem thread and they will be able to take care of it.
There's a chance I might make this repair tool public, but I'm slightly leery about it. If I do I'll let people know.