I don’t have the project anymore but I read on the forums that the 3D widgets are “in the world” where as normal UMG elements are not. Meaning that the 3D widgets are affected by lighting, AA and post effects like motion blur and so on.
That was my problem, I didn’t want that. I tried creating an unlit material for a 3D widget and it just flat out wouldn’t display on them, where it displayed perfectly fine on normal UMG widgets.
It’s experimental of course, so I’m figuring there’s a lot of bugs that need to be ironed out.