Darktide gear upgrade error

i upgraded a blue to a purple it had a rifle it had a 4 cube perk on it when i bought 10percent weak spot damage. as soon as i upgraded it ,it put a locked 2 cube perk on it. this was on my psyker . never upgraded first perk so why did it lock on crappie 2 cube perk. can i get this fixed or was there some reason for it to auto lock like that. or isnt psker hard enough . Has this happened to anyone else?