[Gameplay] TP greyed out, possible Fiora-specific bug

I was playing a ranked game as Fiora top, I had just died and was about to TP back to lane, but the teleport was greyed out. When I attempted to cast it, a tooltip appeared "You cannot use this skill/ability right now".

Once I got back to lane and began to CS, it spontaneously became available to use again (regained colour.)

When googling the bug, the only relevant thing I found was this bug report, so it's possible that this is a Fiora-specific bug. I believe it might have something to do with dying while using Lunge (Q), as when Fiora uses lunge TP greys during the animation video for reference with the grey TP bug. I hope this can be resolved asap, it's pretty debilitating.