Currently, it appears that Setting a GlobalResource Style to be based on another GlobalResource Style creates a XAML error.

Repro Steps:

1) Download and open the attached Project, and open the MainPage.xaml.
2) Open the Resources Panel, and visually inspect that all Resources are contained within GlobalResources.xaml
3) Right-Click on the YELLOW tile on the Stage, and from its ContextMenu, select 'Style', then 'Edit'. This will open the 'Derivative' Styled for Edit.

4) In the Style Dummy Editor, select the STYLE from the Navigator, and from the top of the Properties Panel, set its 'BasedOn' Property to be BasedOn the Style named 'CheckBox_Style_Base'.

Observe how a XAML Error is produced.

Expected Results: Supported and valid "BasedOn" operations don't produce XAML errors.

5) Open GlobalResources.xaml in VSCode

Observe how the error appears to be related to the Resource being referenced as a StaticResource.