[GAMEPLAY] Unstoppable Force stopped by Cataclysm

In my most recent aram game, I had a most puzzling bug in the last teamfight which lost us the game (we never had a chance, even if the bug had not been there. :p). As I was heading, in ult, towards two targets, Jarvan ulted one of my teammates close to me and it was like the game ported me back into the ult, as if I had been on the edge of Cataclysm and "pulled" in. Seing as Unstoppable Force should be, well, unstoppable, I guess it can only qualify as a bug? Since it happened in aram and I hardly ever play Malphite, this is the first and only time I've encountered the bug. The many things that have to be together to actually produce the bug should make it a minor bug, but as a Malphite, losing your ult is tough. :)