There are multiple reasons the PIS doesn’t work on most routes. general rule in practice is if the locos that came with the pack aren’t working, then that’s a bug other locos layered in will most times have an issue of lack of new destination options, therefore displaying blank or nicht einsteigen (or country equivalent) platform PIS tends to be missing off world destinations therefore displaying end route stations as the penultimate stop or blank. Pretty much any other thing wrong with platform PIS is a bug or missed in development.
I’m talking about the DB BR 403/406, so it’s a bug then, or lazy development, probably lazy development, especially since it has never been fixed. So they probably just don’t care, and never will.
Is this ICE 3 the default SKW version, or is it a Livery Designer 403/406 layered from another route? The Köln and München versions don't have destination databases for Kassel-Würzburg