I had an issue where after updating to Catalina (dumb idea on first release
) my monitor on a displaylink-powered dongle was blurry and had a weirdish res being stretched to 1920x1200. (Probably rendering at 1920x1080 and stretching).
Updated to the beta driver. Screen black. Nothing to do but just unplug it.
Today's Catalina update got applied and now the screen works perfectly again - maybe the update process rebuilds something /shrug.
But worth a go for anyone suffering Black Screen Blues.