I too have the issue of the remote main view screen being (1) blank when I'm plugged into a second screen or (2) showing my desktop when I'm only using one screen (even when "Show Presentation" is selected).
The issue with changing the custom scaling is that everything on your computer becomes smaller.
My laptop is on 150% scaling in order for everything to be a normal size. But at this scaling, OpenLP's UI is too large.
When I decrease scaling to 125%, OpenLP's UI is smaller than it was in 2.4.6 (the previous version I used, in which I didn't have this problem). And of course everything else on my computer is then smaller.
So this solution isn't really working for me.
