And I found a way AROUND it.
https://www.macworld.com/article/549...a-scaling.html
Read this article, and review the setup. I created a dummy display, set the resolution and then mirrored the display to the dummy and it works flawlessly. I now have 1080p on the 2nd display. This wasn't the intended use of the hack which was meant for upscaling but this definitely works for the other direction as well.
Obviously you would need to know which resolutions are supported on the display, but it allows for a reasonable workaround.
Also oddly enough, the usual Netflix and streaming issues with DRM/protected content seem to go away doing this as well. I can watch something and not have it black screen. Weird.