PineBuds Pro - pairing from laptop cli - one earbud only

[c6Q$!]

I'm trying to pair my PineBuds Pro using `bluetoothctl` from the command line on my laptop running Arch Linux. I can only pair to one earbud.

Steps to reproduce:

1. Remove earbuds from case. Both buds flash blue repeatedly.
   
2. L flashes red/blue; R flashes blue only
   
3. Enter bluetoothctl interactive mode with `bluetoothctl`
   
4. Scan for devices with `scan on`
   
5. Lists bluetooth devices
   
6. `pair <MAC address>` labelled PineBuds Pro
   
7. Left earbud announces "pairing complete"
   
8. Play music. Sound comes through left earbud only.
   

The earbuds are fully charged, paired, trusted and connected, but I can only pair with one earbud!

Has anyone else encountered this problem?

Thanks.

PS The earbuds work fine with my Android phone. The laptop works fine with a different bluetooth speaker.