Kha ult cancels MordeKaiser ult? Weird interaction all around.

So i was playing some games with the new Morde and this Kha comes to gank me And i ult him just as he used his R and my Death realm(R) never went off, Is that supposed to happen? I know Cleanse and QSs or clearing cc abilities or invulnerable cancels it , but stealth? And one other time i tried ulting him again while as he went stealthed and my Death Realm worked on him, so is that intentional or not.