Bluetooth - Paired but can't connect

[daveozzz]

Having this same problem connecting to 7.3.0.
Android (Mi A2 - jasmine_sprout - android 10) will pair to Moode Bluetooth but the device only stays in the "Currently Connected" list for a couple of seconds and drops off.
If I try to Connect again, nothing happens - seems to just ignore the request.
I've tried removing the devices so neither know of the other, rebooting both, and repeating the pairing process but it always falls at the same hurdle.

I made a tiny bit of progress connecting to Moode Bluetooth (on my Pi4 - forgot to mention that bit) from android.
I activated SSH terminal and did a "sudo bluetoothctl"

I was able to pair and connect via the command line - once. 
I did:
scan on
pair XX:XX:XX:XX


It then went through the additional stage of displaying a confirmation on the phone (which it has never done before connecting from the phone or Moode).

And it successfully connected. I played some music from my phone via the Pi. Then I tested if I would still be able to connect after a reboot of the Pi - and, no, no I couldn't. I was back to connecting for a second and then disconnecting.

And now I can't connect via the command line even if I "forget XX:XX:XX:XX" and start from scratch.

After the initial pairing, I get disconnected. The subsequent "connect XX:XX:XX:XX" command return an error "failed to connect: org.bluez.error.failed"