Black bars (pillarboxed) on ARD connection

New user to RDM and I'm trying to figure out how to get my remote session display to fill my screen.

I've tried turning "Scaled" on & off, no change. Tried using a virtual display, and using a HDMI dummy plug, but no change. And I've tried multiple screen resolutions, but no change.

I am sure I'm missing an obvious setting somewhere but my Google & forum searching haven't turned up a solution.