So I've reached level 50... and I still have 5 dogtags in the "Mystery" category which I can't unlock.
Apart from levelling up, how else do you get dogtag unlocks?
Rebooting and levelling up again doesn't give me any dog tag unlocks; neither do skill assessments

its probably cause some of tags u unlocked vanish like mine i had around 10 dogtags gone missing, 3 weapon, around 7 attachments, 4 nades!

You already unlocked them, the game thinks you've already spent the unlock, and then they disappeared so that you can never get them back?
I wish Crytek could fix this don't you?