Repro Steps:

SCENARIO 1: 'ADD KEYFRAME' CRASH

1) Create a Page
2) Navigate to the Animation Panel, and then into the 'Storyboards' tab.
3) Select the RootGrid, which should have a Background value of "No Brush". If it does contain a value, delete the Page and restart at Step 1).
4) Within the Storyboards Panel, create a new Storyboard, then enter it to edit it.
5) Select the RootGrid, and hover over its 'Background' property.
6) From the 3-Dot menu that appears on hover, select 'Create Keyframe'.

Observe Studio crashing.

Expected Results: A 'No Brush' value should be able to be keyed without crashing the application.

SCENARIO 2: BACKGROUND PROPERTIES NOT DETECTED

1) Create a Page
2) Navigate to the Animation Panel, and then into the 'Storyboards' tab.
3) Select the RootGrid, which should have a Background value of "No Brush". If it does contain a value, delete the Page and restart at Step 1).
4) Within the Storyboards Panel, create a new Storyboard, then enter it to edit it.
5) Move the Playhead on the Timeline to a point in time (I did mine on the 1-second mark)
6) Click on the RootGrid's 'Background' property, and from the colour picker, select any Solid Colour Brush.

Observe how a keyframe was not automatically keyed when the Background Property was changed (from No Brush to a Solid Colour Brush).

Bonus Steps:
7) Still within the storyboard from the previous steps, drag the playhead to the first frame.

8) Select the RootGrid, and from the 'Background' property, open the Colour Picker, and select the 'No Brush' tab.
Observe how the Property's readout in the Property Panel does not update to reflect the 'No Brush' value, but instead displays the colour value from later on in the animation.

9) Hover over the RootGrid's Background property, select the 3-Dot menu, and select "Create Keyframe".
Observe Studio crashing.

Expected Results: The Storyboard system considers a 'No Brush' value as a valid property, and therefore is able to detect a change in value from 'No Value' to an otherwise-valid value.