This is really bugging me now, i'll unlock stuff, but then later its missing again, this also means its locking out those skill assessments.

Example, i unlock grendel and hammer, equip them to a custom class, play the game (with those weapons), but if i return to the customize equipment screen later, they are locked again, and i've lost any kill stats i earned with them. Why does it keep resetting what i unlock!?

I'm having the same issues, as I think pretty much everyone else is as well. Hopefully the upcoming patch will fix this, and many other issues.