Renekton W bug

I am a Renekton main and i have been seeing this bug happen more and more, i'm not completely sure what triggers this bug tho, it makes your w disappear and go on cool down also i think it stops basic attacks on the target, I think it might be when you cast w at the exact same time a shield is applied to the target of your w, i hope this is seen and i hope it helps resolve this problem quickly. its got me killed a good few times ^^