Malazahar bug Interaction with Ekko Ult

So, just got out of a game playing Malz against an Ekko, and we both noticed an odd interaction when Ekko was able to ult while in Malazahar's ult. For whatever reason, it kept Malzahar stuck in the channelling animation after Ekko ulted, and I couldn't seem to move him out of it till the "channel" had finished, despite the fact that Ekko was no longer in the ult. Not sure if it was just a one off thing or some kind of weird interaction because of the way Ekko's ult interact with Malz's ult and vice-verse.