We cover the full solution Here.
In Summary:
- Control + M to switch to Windowed from fullscreen. This will allow you to do the fix:
- Go to System Preferences > Security & Privacy > Privacy > Accessibility. If Heroes of the Storm is listed here, make sure it is checked. If the game is not listed here, you can proc the permissions prompt by checking the Disable OS Keyboard Shortcuts option in the Mouse & Keyboard settings of the game.
If you confirm the issue continues after you completed both steps above, post in the forum post I linked.