When I power on my 700 NC headphones noise cancellation is deactivated? However the headphones still think the phone is on ANC level 10. I have to use the button to cycle through my favorites, or use the app to change to a different ANC level and change back to 10. Its a new bug, but consistent the past 2 months.
As you say this has been consistent for the past 2 months, did you notice anything change before it started? Have you been using the headphones with a new phone or anything like that?
As something that would definitely be worth checking, in the noise-cancellation settings, do you have the Remember My Last Setting options enabled? Does the behavior change at all if you change this setting?
Let me know so I can look into this further with you.