Since today’s update came, there have been random occurrences of the mouse disappearing in the post-game screen where you view Masteries and Performance, being unable to skip them or press continue. Right now this is only occurring in Hunt 2.0 matches. I also mention that it wasn’t just an invisible mouse, but a non-existing one, where you can’t even guess where your mouse would be to hit the button.
Strange, what happens if you open the Steam Overlay when you get this? Also, try right clicking once and see if that helps.
Steam overlay didn’t fix, but after a restart, everything is working fine for now.