Can't exit temple room

Hi i've killed every mobs in a prosthetic research but i can't exit the room it's the second time it happend too me in this exact room this room is between 2 steel flesh quarters is it can help

I've had this happen. It's always been an "untargetable" monster that hasn't activated yet. If you can attack a monster in the next room and pull it back through the door it will activate your idle mob and you can proceed. If not just stand on it and keep casting, after a minute or two it will come alive and become killable. Annoying as F, good luck!