Currently, there are instances where a Global Resource can't be applied to a Property if said Property is being 'overridden'.

If I'm not mistaken, applying a Resource should technically be possible, even the Property value eventually gets overridden by a value in a different location.

Repro Steps:

1) Download, Unzip, and open the attached Studio Project.

2) Navigate to the Resources Panel, select 'GlobalResources.xaml
Observe how there is a LinearGradient Brush present,

3) In MainPage.xaml, right-click on 'Button2', and in its context menu, navigate to 'Styles'->'Button'-->'Edit Current'.
This will open the Button Style in the Inline Dummy Style Editor.

4) Hover over both the striked-through 'Background' Property, and click on its 3-Dot menu.
Observe how the 'Apply Resource' option is greyed out and disabled despite the fact that the LinearGradientBrush GlobalResource Resource should be accessible by this Style.

Expected Results: GlobalResources are accessible and can be applied at any level of the Project.