Currently, there appears to be an intermittent bug where all of the Dictionaries that are Merged into GlobalResources (or merged into other Dictionaries Merged into GlobalResources) do not display in the Resources Panel until the Page is closed and re-opened.

Video attached.

Repro Steps:

1) Create a new Project featuring a MainPage.xaml

2) In the Project Root, create a new ResourceDictionary named "Dictionary_Master_1.xaml"

3) In the Project Root, create a new ResourceDictionary named "Dictionary_Colors_1.xaml"

4) From the Resources Panel, merge 'Dictionary_Master_1.xaml' into the GlobalResources Dictionary.

5) Select 'Dictionary_Master_1.xaml' so that its tab is open.

6) Merge 'Dictionary_Colors_1.xaml' into 'Dictionary_Master_1.xaml'

7) With the Resources Panel open, cycle through every open tab ('MainPage.xaml', 'Dictionary_Master_1.xaml', 'Dictionary_Colors_1.xaml', and 'GlobalResources.xaml')

Observe how throughout this cycling, in the Resources Panel, in every open document, is visible under the 'Application Resources':
--GlobalResources.xaml
----Dictionary_Master_1.xaml
------Dictionary_Colors_1.xaml

8) Return to the Assets Panel, and under the Project Root, create a new ResourceDictionary named "Dictionary_Typography_1.xaml".

9) Open the Dictionary_1_Master.xaml tab, and in the Resources Panel, merge 'Dictionary_Typography_1.xaml' into 'Dictionary_1_Master.xaml'

10) With the Resources Panel open, cycle through every open tab ('MainPage.xaml', 'Dictionary_Master_1.xaml', 'Dictionary_Colors_1.xaml', 'GlobalResources.xaml', and 'Dictionary_Typography_1.xaml')

Observe how all Documents, except 'Dictionary_Typography_1' , all display the same dictionaries under the ApplicationResources.
Observe how 'Dictionary_Typography_1' is missing showing itself under GlobalResources.xaml/Dictionary_Master_1.xaml.

11) Close and re-open Dictionary_Typography_1.xaml

Observe how now, in the Resources Panel, that 'Dictionary_Typography_1' is now visible under the Application Resources.

Expected Results: The GlobalResources children and grandchildren manifest visible inn the Resources Panel is universal across all tabs.