Hello,
1) Yes, the first monitor has the settings in the screenshot, while the second is a 1920x1200 and the size of text is 100%.
2) The primary monitor is the 1920x1080 one and the second, placed on the right of the first one is the 1920x1200 one.
3) I am using version 18.2.0.56 and I am developing using .NET Core 3.1.
Your sample works correctly. I'll try to create a stripped down version of my project to attach here to show my code.
In the meantime, thank you for your quick response!
Luca