I've noticed it has something to do with the Stroke Property.
See these notes:
With StrokeCode: Select all
<Path
Canvas.Left="0"
Fill="WhiteSmoke"
Stroke="Transparent"
Data="M18.1,4.8C18,4.3 17.6,4 17.1,4H13L13.2,7H10.8L11,4H6.8C6.3,4 5.9,4.4 5.8,4.8L3.1,18.8C3,19.4 3.5,20 4.1,20H10L10.3,15H13.7L14,20H19.8C20.4,20 20.9,19.4 20.8,18.8L18.1,4.8M10.4,13L10.6,9H13.2L13.4,13H10.4Z" />
Chrome: Works as expected
Firefox: Works as expected
IE and Edge: Fill flashes on load, then disappears. On Resize Browser window, Fill loads color.
Without StrokeCode: Select all
<Path
Canvas.Left="0"
Fill="WhiteSmoke"
Data="M18.1,4.8C18,4.3 17.6,4 17.1,4H13L13.2,7H10.8L11,4H6.8C6.3,4 5.9,4.4 5.8,4.8L3.1,18.8C3,19.4 3.5,20 4.1,20H10L10.3,15H13.7L14,20H19.8C20.4,20 20.9,19.4 20.8,18.8L18.1,4.8M10.4,13L10.6,9H13.2L13.4,13H10.4Z" />
Chrome: Works as expected
Firefox: Works as expected
IE and Edge: Fill loads color.
On Resize Browser window, Fill DISAPPEARS!