Currently, there appears to be an issue

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 RED tile on the Stage, and from its ContextMenu, select 'Style', then 'Edit'. This will open the 'Red' Style 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 with "YELLOW" in its name.

Observe how the Resource has not been successfully applied as the 'BasedOn'.

Expected Results: Setting one Style to be BasedOn another, sets it as the Property's value, and populates all other Properties accordingly.