Sorry for the late reply, but I wanted to update my findings and let you know that this case can be closed, and that I found out what the problem was with not all my combos going off. It's because my characters were all to high of level (37+) and they ended up killing the giants before they could finish doing all the disco moves to complete the combo.
Only solution I found was to either limit the combos to 2 either combo Rave Steal / Rave Nirvana or Rave Nirvana / Disco Nirvana or just ascend and reset the level.
Only solution I found was to either limit the combos to 2 either combo Rave Steal / Rave Nirvana or Rave Nirvana / Disco Nirvana or just ascend and reset the level.