The video is not updating while rinning StarCraft 2 via Parallels Access, and I cannot switch to another application using App Switcher. The Unstable Internet connection error is displayed.
Swipe across the right edge of your screen to show the toolbar. Click on the keyboard icon to launch the keyboard.
Click Cmd+Tab, and you will switch to another application.
Now you can get back to the game and the issue should be fixed.