Fiora bug - unable to use summoner spells

I've played some Fiora games recently, and I have found that around about the mid-game or so, when I die and respawn, the game is not allowing me to use either of my summoner spells, despite them being off cooldown. It has happened in each of my past few Fiora games, and is preventing me from teleporting straight from base, which can be game-changing. Just play Fiora and die around about the mid-game to reproduce this bug, from my experience. I have not found any other factors affect the production of this bug.