As discovered by a Reddit user, Apple seems to be shipping replacement single AirPods with a new, unreleased firmware which is preventing customers from using them with their old ones (via iMore). Since the new firmware has not yet been released by Apple, the existing AirPods can’t be updated to it either.
The two AirPods need to be running the same firmware in order to pair with each other. The replacement single AirPods are said to be running an unreleased firmware version labelled ‘2D3,’ which when paired with the other AirPod running an older version of the firmware, do not seem to work.
“I’ve spent about 10 hours over the last week on the phone with various level 2 technicians, as well as some more hours troubleshooting,” noted the Reddit user.
“I want to thank all the various (nine) technicians who spoke with me. I tried my best to be kind, patient and understanding In the midst of frustration and confusion. They were as helpful as they could be.”
[…] this appears to mainly be impacting AirPods (2nd Generation) although there are sporadic reports of AirPods Pro earbuds also being received with firmware 2D3 installed.
Apple is yet to issue an official comment or a temporary fix regarding the matter.