Hi @Teun, your post is very welcome in our community.
My name is Wiliam, I am an Independent Consultant and like you, I'm also a user of the Windows system for a long time. I am grateful to be able to help you today.
I understand how difficult it is when the device or app won't work in the way you expect, but I found information on the Sony website stating that "Headphones (WH-1000XM4 Stereo)" is only used for music playback and for "speaker and Microphone ", you should user "Headset (WH-1000XM4 Hands-Free)". Follow and info from Sony for reference:
[https://www.sony.com/electronics/support/wirele...](https://www.sony.com/electronics/support/wireless-headphones-bluetooth-headphones/wh-1000xm4/articles/00250089)
They also inform that these options may differ depending on the app you are using and If the list shows only the headphones model name and does not suggest the purpose of use (for Hands-Free or Stereo), select your headphones model name.
Anyway, please take a look at this solution provided by another community member, which helped lots of people with similar issues:
[https://answers.microsoft.com/en-us/windows/for...](https://answers.microsoft.com/en-us/windows/forum/all/bluetooth-sound-output-with-sony-wh-1000xm4/5267693b-f825-49b8-ae88-b400061d776d)
Credits: Ragnar Fredrik Johansen
Please let me know if you need any further assistance regarding this matter?
Best Regards
Wiliam D.