Bug explanation

When setting BorderThickness and BorderBrush on a SnackBar, these settings aren't reflected on the template as the border doesn't have these properties template bound.

Suggested solution is to implement the following lines to the SnackBar Style, in the Border object:

BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"

Version

5.2.1