hm that seems not to happen to all of em, i had yesterday 3 time capsules fights on my lvl 11 controller and 2 of em was over in seconds.
Maybe it depends on mob types used for it, one spawn was family, the 2nd was warriors, the 3rd one i didnt want to do, cause "riki" well damage resistance.....
and by OP the family men with 68 HP seemed to be ok, the nemesis with over 300 naturally not.