BT volume no longer linked? BT devices can't control system volume anymore

[talz13]

So for as long as I can remember, my launch day OP5 has responded to BT volume changes (e.g. I turn the volume up or down from the BT device, speaker, or headphones, and the volume level on the phone is adjusted). Recently, I've noticed that this is no longer the case. I have tried both enabling and disabling that Developer Options > Disable absolute volume, but haven't been able to get back to the state I was in before.

I've tested with my Jabra Elite Sport headphones, and my Tribit XSound Go... But neither of them will make the phone volume level change...