No matter how much you hate PHPBB, that's not such a bad idea. Now I shall go to wherever you point me to if I have any future suggestions.
And now, to get back to the topic: I don't know. I have 3.4 and 3.5, and I don't have that problem. Then again, since I have never used custom models and the original models are in the pak file so Hammer can't read them, I never had this problem.