I seem to have just had this problem with a new Lenovo laptop. I tried for the first time to use my Samsung bluetooth earbuds in a WhatsApp call and I got the audio but it didn't recognize the microphone, "Headset" didn't show up in the list of Input devices in the sound settings.
Suggested by older posts in this thread I remembered that I'd installed all the optional windows updates too including all the drivers. So I just went to the Apps and uninstalled the Realtek audio thing, then rebooted. Now it works.