Lux R not working on the latest Nexus Blitz game during Bardle Royale: Juggernaut

I shared a dropbox link above to part of the replay of the game (it is a sad sad game) but during the third event, Bardle Royale: Juggernaut, you will see me by the bot side then by the inhib. kinda doing nothing just throwing my abilities, and then as the circle closes in on me, I ult. pretty much nothing in the bot lane. In the meantime, IRL, I was spamming my R (ultimate) key and nothing was happening.

You will see it looked like the ult. was on cooldown in the replay but on my side in-game it definitely showed off cooldown. I know this because I was staring at the HUD after my ult didn't go off the first time. I thought, "it must be on cd" but then I looked and it wasn't on cd in my HUD.

Is it possible to see what I was seeing in game? If so, can someone look at this possible bug?

Much thanks!