Turns out you can report Win10 bugs with the “Feedback Hub” App that comes with it.
Not as good as a proper bugtracker, apparently not even readable via browser, but better than nothing…
I think it allows you to vote on bugs, and if you’re on Win10 the following URL should open the bugreport in Feedback Hub: https://aka.ms/W2icb9
Maybe if some people vote there this gets fixed faster :-)