Going to play story missions or operations, Beatrix has become locked. I bought the season pass, unlocked Alani first and then unlocked Beatrix. I played The Algorythm with Beatrix (solo) and then today played the first operation today (solo). When I went to repeat the operation (solo) with her she was locked. I played it with Orendi instead. I then unlocked the rest of the characters because I though might as well. I then tried the first operation again. Only Beatrix is locked.
As you can see she is not locked in the command centre. I have restarted the game to no avail.