Hi,
Can you let us know if the scaling option selected is Center Image or Maintain Aspect Ratio when you play the game at lower resolution? One alternative solution if you want to run the game in 'Full Screen' is you have to go to CUI>Display page and select 'Full Screen' option under Scaling.
We are working on the solution to provide all the scaling options in the native resolution. Will keep you posted once the drivers are ready with the fix.
Thanks,
Sowmya