When I add a button to my frame, the frame loses the ability to render any other graphics except macos native UI elements on the frame. Actives, Backdrops all disappear and I'm just left with a gray background.
Running Monterey on an M1 Max.
See the attached example file. Build a Mac App as-is and you'll just get a gray box with the button. Delete the button and build it again and you'll have the frame as designed.
button-294.4-test.mfa