first of all, i didn't see a topic with this problem, if there is i'm sorry for not noticing that.
I have encountered a bug where you get a high level (20) reward from Inquisitor level up reward "chest".
I already have Crusader on level 20 and these rewards are from second character assasin on levels 2, 3 and 4 as seen on screenshots.
It affects only Inqusitor level up rewards, not mission rewards.
[screenshot for lvl 4 is missing, forgot to tap button :D]
it seems to be present in every time i level up and open a reward for it. Usualy it picks newly unlocked weapon type.