Looks like you are right. FiA only seem to work for premier shows and not for programs that are on hiatus. Which means, that if hiatus shows must stay in the Series Manager, the Series Manager limit needs to be at least double.
Ok, I didn't realize there was a difference between shows on hiatus and things that haven't premiered yet. Not sure i'm suggesting increasing an increase to Series Manager (but i wouldn't complain if they did) but it would be nice to be able to schedule FIA for shows that are on hiatus.