I by no means, am ANY way a pc expert - HOWEVER, I was really upset at not being able to play the game and couldn't figure out why. Had the exact same issues. Here's what finally fixed it for me after trying multiple things (reinstalling, etc.).
- Go to your game folder. Locate, then right click on the StardockLauncher icon, select Properties - go to the Compatibility tab, under Settings, check the "Disable FullScreen Optimizations" box. Doing this in the game launch icon didn't work for me. Doing it in the StardockLauncher icon did.
The game now opens in full screen without any issues! I sure hope this helps you.