I want to start getting the appearances on my characters who are eligible, but Kalec is nowhere to be found (he isn’t in the class hall and isn’t in Azsuna). I meet the requirements on those characters, and have seen him in my class halls back during Legion, but no dice.
After you meet the requirements, it can take a couple of days before he actually shows up in the class hall. So, once you’ve done the pre-reqs all you can do is wait.
I’m not sure what the case is if you did did all the requirements a while back. It may be that something resets if you haven’t been to the class hall for a bit, and it may take him a day or two to show up again.