Yes, the “application bar icon” is only used on Windows Phone 8.1 or earlier, and in practice, UWP uses the environment to view applications in the store. StoreLogo is actually a small icon and is used in the respective scenarios (as you already mentioned).
A possible workaround might be the following:
- use the solid color icon as the default tile to use in the vault, and
- refresh the tile with another transparent image after starting the application (just do not specify the expiration date).
ps Some applications also use this approach to provide users with a choice whether they prefer to use the corporate color on the tile or use the color accent system.
source share