A certain richardlennoxyz on the Apple Support Communities has this solution:
1 Connect Device
2 Go to settings, right click on device, dont click the menu, leave it open
3 Turn off device
4 Select "rename" in the still open right click menue
5 rename the device and close the pop up
6 Turn device back on and connect
Settings refers to the Bluetooth preference pane for clarity.
This was awesome, I'd nearly pulled out my remaining hair before finally tracking down this ASC forum post.
Can't believe this actually worked. Hilarious. Apple's software continues to decline...