How many devices can be with 1 Apple ID?
I already have 6 devices to 1 ID. Is that the limit? Got new AirPods Pro but they don’t show up in my devices.
iPhone 12, iOS 18
View and remove your devices that are associated with your Apple Account for purchases - Apple Support
"You can have ten devices (no more than five of them computers) associated with your Apple ID and iTunes at one time."
That's for purchases. I don't know of any limit for general account association and certainly not anything that would explain your issue. Have you tried restarting your devices so they take a fresh look at configuration?