Ritual Monster that cant Die

There are some cute Little guys, i think they called Kinn or something like that, that wont die in every Rituarl, they are in.

U have to relog to end the Ritual.
I testet 5 Minutes , if there is some hidden monster, but i cant find one.
After 4 Times of 7 Ritual Maps, i think this is hopefully a known issue, or someone got an Answer, how u can handle it.