Frequently the in game cursor becomes invisible during game play , it’s still there and you can click on stuff, but makes it very difficult to select heros. The only way to return it to normal is reloading the game. I’m also not sure what triggers this.
same thing here … very annoying 
So I’ve found out this happens when you alt tab out of the game while there is no menu up, if you bring up a menu and alt tab out again it also fixes the problem.
Same as:
And this:
And this: