Cannot update firmware on AirPods Max, model A2096—firmware version 3C39.

I have AirPods Max, model A2096. Firmware version 3C39. I tried to connect them to iPad Pro, iPhone 15 Pro Max, Macbook Air M1, and iPhone 12 - and still cannot get them updated to the latest firmware version.

I am following all the instructions: connect to the Apple device, put them into the case, plug in the charging cable. Both AirPods and iPhone or Macbook have to be in the Wi-Fi network.

Please advise, thanks in advance!