Zain Has no unlock mission but its locked

Hi @RD_L3g3nD I'm not near my Xbox to check myself, but the information I'm seeing on Reddit etc is that the requirements are 30 Hipfire kills, and 750 damage with under-barrel grenade launchers*. Hopefully, that's correct.

You should also be able to see the requirements if you tab over to "Collection" and view the Specialists there instead of in the "Classes" section.

*I'd recommend not using the UB launchers on Portal weapons, like the M16A3, as those don't always count towards unlocks. Using the one for the M5A3 should work well enough, though.