Currently, when setting up a Trigger Action, the 'Property Name' of the 'Target' to modify typically offers a selection of Properties to pick from, and assign a new value to.

However, in the case of selecting a Target that has Attached Properties, these Attached Properties are not available to select from the list.

See attached image.

Repro Steps:

1) Open the 'Sizzle' (Drag&Drop) Sample from the InternalProjects GitHub.

2) On MainPage.xaml, identify, then select the 'Page_Grid' Element in the Navigator (Under Page/Master_Grid/Page_LayoutScaler).

3) With 'Page_Grid' selected, navigate to its Properties and expand its 'Drag and Drop' Properties Category.

4) Make a mental note of the Properties found here. (Overlay Host, Overlay Template, Transfer Key, and Transfer Mouse Button).

5) Keeping 'Page_Grid' still selected, navigate to the Interactivity/Triggers Panel, and create a new DataTrigger for 'Page_Grid'.
Doing so will display the created Trigger's Properties in the Properties Panel.

6) Under the Trigger's 'Actions', create a new Action of type of 'ChangePropertyAction', and set a 'Target' of 'Page_Grid'.

7) Still in the Trigger Action, expand the 'Property Name' dropdown, and search for any of the Properties recorded in Step 4).

Observe how none of the Drag and Drop Properties are available to select from despite being valid, and populated Properties of the Element selected.

Expected Results: Attached Properties are available to select from throughout Studio.