This ability works so randomly. I already have it in instant casting to minimize the issues, but they still occur. Sometimes you can use it normally and sometimes it gets glitched and does not allow you to hit for the second time or you have to spam the button to finally get it. Some matches I'm completely unable to use that one skill regularly the whole game. It's a lottery. From what I know, the community has been conscious of this trouble from a long time now, I don't even get why it's still there.