I don't know either, your case never happend to me. Maybe your affection with Kana or progress with cleansing outer town areas are a condition as well?
You have mention most conditions, but let me list them again, maybe you have forgotten one?
You can only visit a dungeon on the same day as you've cleared it -in other words; If you need church, then you have to wait until you get there to exorcise (weekends does work better, because you can choose where to go). In addition, look out for that swirl of the cleared dungeoin, it is slightly different than the others.
Just to make sure, you probably know that already: Once a day but twice per dungeon -though, you can trigger both events with one visit (it happened to me at the mansion)