Quest level normal issues

Just a quick question. I normally go well with the quest in normal mode, however now at 3rd stage I can’t get any thing done. I get all the enemy down to there last bar and almost all dead but that is where it stops. My GP is 10mil so that is not the issue. Like I said I get them all down or the bear minimum and then I just run out if time. Anyone running into this???they just will not die🤬