Sion Ult Bug

I don't know what caused this. I was trying to use Sion's Flash-Ult combo and at the same time my ult hit yasuo used his ult. But afterwards my character still acted like my ult was on. I could't use my abliities and he was following my cursor with the same graphic as he does with the ult. However I was walking at normal speeds and had no red particle effects. This ended when I reactivated my ult.