Class Mod slot not unlocking

Been playing through a multiplayer game with my friends, we finished the mission Hostile Takeover which unlocked classmods for the both of them but not for me.
I’m currently level 15 and the only member of the party with no class mod slot.

Is there any way to fix this?
I joined my friends game who had not completed the mission yet and still didn’t unlock it even after doing the mission a second time on this character.

Try solo & hopefully you see what your character missed.

I can’t replay the mission in solo because I already completed it with friends can I?

I did just make a new character and sprint to Hostile Takeover as fast as I possibly could and did it in single player and that actually unlocked it for me that time.

Try loading your character in solo and see where you are. In 2 if you were far enough back when you joined a game, you did not get credit. Also you can have you friend try to join your game, because a LVL 40 can join a LVL 1 game and replay the story, but they will not get the rewards / unlocks.