I had a similar issue, but I followed the procedures (I think) and still having issues.
1) Ran through the Bluetooth pairing process from the website and confirmed that my android phone (pixel 6) was paired and trusted.
2) Tried running APRS droid with TNC(kiss) BT SPP | channel 1 | digipi selected device
3) when I click "start tracking" blue tooth icon on digipi screen flashes briefly: APRS Droid shows connecting to the BT address of the digipi and indicates "Could not connect to digipi! Please turn on the device and close other Bluetooth connections" [no other BT connections are active on the phone].
4) here's the verbage from bluetoothctl during the aprsdroid connection (device BT address removed:
hci0 [-BT Address redacted-] type BR/EDR disconnected with reason 0
[CHG] Device [-BT Address redacted-] :EC Connected: no
hci0
[-BT Address redacted-] type BR/EDR connected eir_len 14
[CHG] Device [-BT Address redacted-] :EC Connected: yes
hci0
[-BT Address redacted-] type BR/EDR disconnected with reason 2
[CHG] Device
[-BT Address redacted-] Connected: no
Any insight would be appreciated.