I have already activated my Limited edition promo, successfully and correctly according to the instructions. When I log into MP it pops up confirming as much. Not sure if this is the cause of the below issue...
Everytime I start a new session my rank/stats/achievements all reset back to level 1. When I first log in, it shows I'm rank 5, when I join a game it says I'm too low in rank to use my custom equipment I set up.
From what I've noticed (Atleast in my case) it seems like whenever you get kicked/disconnected from a server, you lose all your progress that you had while playing on that server. If you leave the game it say "Updating player profile" or something, and then you shouldn't have any problems.
But then again, that seem to work for me so i can't really say if this is 100% sure.
Its a problem everyone is getting. If you get disconnected, freeze or crash you lose all your progress for the entire play session to the point where you last manually left a server. The game also sometimes fails to save even when you DO leave a server manually which is rather frustrating. I would guess that most players have lost well over 10,000 EXP due to this problem throughout the course of playing multiplayer.
The game also has problems saving Dog Tag unlocks and distinguishing between new items and old items. Every single time I start multiplayer my modules and some weapons are marked as new when they are not.
Sadly though Crytek is prioritising on single player issues at the moment which is disappointing considering the majority are playing this game for multiplayer. You would think something as major as progress constantly rolling back would be a top priority to fix.