MF ult ignores kayle ult

so i was in last 3 of a ranked game, got my kayle and noble was complete, had some half decent items for my team and was feeling good, then enemy MF starts ulting, my kayle ults right away and my vayne isnt in the ult, so im hoping maybe we have a chance, but mf ult goes right through my kayle ult and kills her leaving my vayne all alone, im pretty sure my shojin kayle and my stacked 3* vayne wouldve done enough to keep me alive, but vayne alone got focused, only killed one enemy unit and i lost all my hp

TLDR mf ult ignored kayle ult