So I've fulfilled the requirements to unlock The Gang's All Here (the one where you recruit all companions). Multiple times. Most times in the same save file. It hasn't unlocked.

Having read that it doesn't even need to be in the same save file, I'm wondering if the file that tracks it is corrupted. Where is it so I can delete it and have Steam redownload it? I feel entitled to this achievement after having done the requirements like 50 times.

If the community doesn't know, I'll ask Beth Support but I'd rather not trouble them unless I have to, since the game runs perfectly fine otherwise.

Hm, it never has unlocked for me, either, although admittedly I didn't actively pursue it it.
Might be that I had used the console before recruiting a companion, as that prevents you from getting achievements until restarting NV.