All settings seem to work fine except for the volume controls. Not sure if its partly the earphones fault, as they actually lack "volume control gesture" on the buds. But the Trust Nika Touch earphones work great when connected to my ZenPhone 6.
Problem #1: The volume controls on the watch does nothing when trying to adjust the volume
Problem #2: The volume starts at an dangerously high level. If the volume was 50 % lower I could probably live with problem #1. Phones know not to blast 130% sound level. Would be great if the Vivoactive 4 could learn this too.
Problem #3: One of the important features and reason I bought this watch was its ability to play and control music....