I have this problem with my xm4. Also my Samsung watch doesn’t sync very well even though it is connected.The issue with the audio on the WF-1000XM4 is an odd one. When I change sources, a lot of times there's only audio from the right bud. So I have to pause the media, tap the left bud, wait a couple of seconds and then resume the media for it to play through both buds.
It's getting a bit annoying so hope they fix it.

