They changed the requirements of these challenges. They lowered the amount you have to do to some of these challenges. So you have the same problem as I have. I had already made progress beyond that lowered requirement, so now ALL of my open challenges are locked which should be now completed. Danger close, Assault, Close quartes etc etc.
UPdate:
At least the Assault Expert 2 closed after I started doing it again and I can start doing the final step. Can't confirm yet the others. I'll post an update when I test those too.
At least for me, all those challenges are now open and I got the guns etc also. I just went through the guns etc in one match and after that the lockdown cleared.
