Mordekaiser W visual disappeared [GAMEPLAY}

The visual effect of Mordekaiser's W disappeared randomly during game and never came back. I had no skin active, used active items Protobelt and Shurelya's and laned against beekeeper singed (idk if either of these lead to the problem). It actually was impossible to tell if my W was toggled or not and made playing the rest of the game very difficult.