Hmm, it could be possible that you haven’t unlocked the quick magazine yet. The quick mag is the only one in the magazine category. It could be that the magazine category doesn’t show up until you have unlocked the quick mag. Other than that I’m not sure what the solution would be. If you believe it is a game issue/ bug I would be sure to document it to the best of your ability and report it to the developers so it can be fixed in the future!