Runed Monolith bug

After having chained bosses without any problem, when the next boss appeared he just stop moving like he was stuck in the remaining tail of a previous boss. When im turning around him he some time attack my minions but me or my minions can't deal any damage to him. Can't use my portal to leave that situation, had to group with a friend and teleport to him. https://postimg.cc/GBHHypQk

i got the same Problem how to fix it ?