Welcome to the forums!
I’ve only got one Gadgeteer project where I’ve worked with Glide, and I think my loading logic is essentially the same as yours:
window = GlideLoader.LoadWindow(Resources.GetString(Resources.StringResources.Screen1));
Is the name of your resource “Window”? I’m wondering whether you might be running into an issue with either an incorrect resource name, or perhaps Window is ambiguous in that context, since both Glide and .NET MF have Window classes defined.
The GetString method itself is implemented in Resources.Designer.cs, so you could check there to ensure that the class didn’t somehow get corrupted.
I may be asking the obvious, but you did add the Glide XML as a string resource, correct?