Enjoying my Sony WF-1000XM4 earbuds! Really catchy name there Sony!
My left ear bud was not working. Tried everything. Turns out all I needed to do was disabled the assistant setting in the Sony app. See screenshot. Mine was set to “Voice Assist Function of Mobile Device”. I don’t use any voice assistants so turning it off worked. I put the earbuds all back into the case then put them in my ears and both worked. Hope this helps someone.