My Mac (OSX 10.8.5) does not appear as one of my Apple ID devices, even though I am signed in.
MacBook Pro with Retina display, OS X Mountain Lion (10.8.5)
You need to be using a newer OS.
Check your Apple ID device list to see where you're signed in - Apple Support
Thank you! I see where it says a device with that OS will not appear. I only discovered this because I could not sign into FaceTime using that computer.
See if you can add it here.
No, it just tells me to add it by signing in to Apple ID using that device, but I am already signed in. It shows my iPhone as the only device.
You are welcome.
Device not showing in Apple ID
