I'm having this problem too from playing through natural progression, which is the reason why I didn't want to go the unlockall route. I only hit 1st prestige on PS3 and never managed to get any further (as I prestiged a few years after I hit max level and the game started dying on PS3 by then), so it doesn't seem right for me to go straight to 15th prestige level 50.
You can still create classes but you lose access to all of your weapons and perks (including pro upgrades), resulting in you having to buy everything you had again.