Missing Third Weapon Slot

From level 1, my boyfriend and I have been playing co-op together, but he played a few missions without me, unlocking his third weapon slot. When I played with him again, I noticed I did not have my third weapon slot unlocked, and am now level 19 with only two weapon slots.
I’ve tried going to single player but cannot go back to the mission where this was rewarded since it starts me off where we last left off together.
Is there a way I can get this slot unlocked without creating a new character?

I’m having the same issue (my third weapon slot is locked). I’m level 30. It says I have completed the mission “Taking Flight” in my mission log, which I’ve heard is the one where you unlock the third weapon slot. Can someone tell me how to fix this?

I thought maybe it’d unlock whenever I unlock the fourth slot at lvl 20 but now I just have three slots and the third is still locked. this is mildly infuriating tbh

I’d say try looking for someone who hasn’t done the mission yet and joining their game to complete the quest again. That might work.

I thought that would fix it too, but it didn’t work unfortunately.

Going on w my brother as party leader and playing through taking flight worked for us. Don’t give up!!