Possible Vi Ultimate bug

Was just playing a game of Vi. Things were appearing normal. I went in for a full channel q. As it landed and did its damage on a TF and MF I was either stunned by a TF gold card, or immediately after landing, knocked up by a Janna Tornado. After all this cc, no more cc was able to be used, but I was not able to use my ultimate whatsoever. I sat beside their Miss Fortune for 5 seconds trying to press ultimate, and it would not cast. I died, and thought well maybe it was just me misclicking, but looked and my fingers were on R. Still I thought it was just me. I resd, and tried to press r on the people finishing the nexus, but it would still not use. I have no idea what happened. My items were refillable potion, tracking blade with warrior, ninja tabi homguard, Sterak's Gaze, Dead Man's Plate, Null magic Mantle, and Warding totem.

My team consisted of braum, vi, jayce, vayne, and leblanc. Enemy team was janna, miss fortune, maokai, twisted fate, and kindred.