Community Manager@EA_LeeuwSounds right now like a new mechanic to prevent people from unlocking stuff in PvE or it's just generally bugged.
Tbh now... just played a round and it appears that the AoW (Solo/Coop) is bugged instead of unlocking attachments/Skins on Mastery 4 and 12 you can unlock those at Mastery 5 and 13 (Had that with Crawford didn't unlocked his skin until i hit Mastery 5 out of 4)
Community Manager@Xherdos, well, there's this issue. Which could be the same as OP is experiencing.
(Hence my question is to make sure that it isn't related to either Solo/Co-op or Portal. 🙂)
Apart from that; in Solo/Co-op (and I believe also in Moderate XP Portal experiences), you can/should only be able to level up your Guns to Mastery 12.
