Malphite's ult bug

I've played Malphite a few games, but for some reasons whenever I try to ult, instead of ulting to the place where I want Malphite to go, he just keeps walking, unless I click on the HUD and use his ult that way

It has happened to me like 4 times already, and I'm not sure if it's intended to do that or if it's a skin bug (Ironside)