Tier 15 map not spawning any rare monsters (cant finish map)

I have a tier 15 map with no rares. It says 0 monsters left and I killed all but there were no rares.

I have an idea why it happened:

The map has a modifier: rare monsters have an 30% chance to have an additional modifier. I also have the atlas nodes for extra modifiers on rare monsters. I think they might not have spawned because they cant have that many modifiers.

Thank you.

I did another map with the same modifier and rares spawned there. I still dont know why they didnt on the other map.

I noticed this was well sometimes.

A map, that has no rare mob when spawning, cannot be finished, because you never killed a rare mob, to check the "map finished" condition.

I the end you are at 0 mobs, but the map is not marked as fininished. I just ran them again with a T1 stone, just to get it away.