Hi, I had the same problem, my Cali, Ayneris, and Maple were all locked out of my combat group despite meeting all the requirements. After looking over my save files the problem seemed to have happened in one of the previous version but i did not really notice it at the time.
After some random testing I was able to fix this problem by putting said characters in jail and ending the day. On the second day I released them back into communal and everything was back to normal. Hope this fixes your problem.
Ver. 0.5.22b
Macbook pro (MacOS Sierra)