Crash when creating an animation

The editor crashes when trying to add an animation key frame for the row fill setting for a grid panel

1. Open the editor
2. Create a new widget blueprint
3. Add a Grid panel to the designer tab
4. Create a new widget animation
5. Add an element to the row fill for the grid panel
6. Set the row fill to 1 (important, does not appear to crash when set to 0)
7. Click the add key frame button next to the row fill

Result: The editor will crash
Expected: A key from would be set for the row fill option