PHENICUS wrote:
I have my screen resolution set to 3840x2160. Is it possible that those settings are causing some issue?
That can indeed be the reason. I was almost going to ask whether a 4k display might be involved. While Windows 10 is able to enlarge many window elements, to make them look "normal" size, it seems to fail for others.
The map tile preview area in TransDEM is set to 512x512 physical pixels, and you most probably get these 512 physical pixels, while most other elements will be twice the original size on your display. I have not figured out any pattern here yet. On my tiny 10" Win 10 laptop with a higher than normal physical screen resolution, I have set the display zoom factor to 125% to make things legible. And there the preview image does fill the entire designated preview area.