Not sure this is related but , I have noticed odd button scaling as well. Surface book 3 with 200% scaling using 3000×2000 using the built-in display and a external monitor with 100% scaling using 1920×1080. If I start the unit with the external display attached I get the expected results, see attached. If I start the unit without the external display and then attach the docking station I get the one labeled unexpected results. Closing and restarting DI resolves it.
Also noticed I am not able to move DI around the screen with this version.