Sorry that i dont have a screenshot or something else. But:
While playing legendary event on the stage where Marie-Therese stands as boss alone with two mobs with her, i noticed the known issue that after she fired her skill, and I fired mine (wilbur, khagan, azlarC) the zombie minions that logically will be “born”, where invisible.
I know a while ago there have been some invisible revived enemy problems, I guess it has somethin to do with it and should not be left unmentionned.