[GAMEPLAY] Riven's Valor becomes uncastable until Broken Wings is used

As the title says, Riven's third ability, Valor, is uncastable in some cases: the skill icon becomes colorless, as if I have never put a skill point in it, and it stays like so for as long as I don't cast Broken Wing. I'm unfortunately unable to reproduce the bug, but it happens at least once per game, I noticed it always happens if I die and I haven't finished casting Broken Wings. Considering casting Broken Wings also greys out Valor for the duration of the animation, my idea was if I die during the animation of Broken Wings, my Valor would be stuck in "animation not finishing". I unfortunately can't make that happen in custom game suiciding to turret, but like it I said it happens around once per game, so I think it's an identifiable bug. Another possibility would be if I die while stunned.

I don't know how to upload pictures I hope my text is clear enough.