I just played a game where I was unable to cast Q or recall for a long time. It seemed to fix itself after I ulted. I think the bug occurred after I ulted in a previous fight, so I think when I got interrupted during an ult it bugged out my recall and Q.

I just had a similar experience. My best guess is that it was because sivir spell shielded my ult. After casting it, I seemed to have disappeared from the map for a second or two and then I reappeared where I had initially casted my ult. That could be working as intended as the spell was blocked, but I was unable to use my Q or recall for a period of time thereafter. Disconnecting and reconnecting didn't fix it. It wasn't until I died that I regained control of my Q and recall. Nothing else seemed out of place though.