I struggled a lot to connect my new Mares Puck 4 to Subsurface /Android App).
Finally, after many attempts, I found the following sequence:
1) Wait for the Mares Puck 4 computer to turn off, with a blank screen.
2) Set the Subsurface Android app ver. 6.0.5612-local to Advanced > Temporarily show all Bluetooth devices.
3) Go back to "Add dive from computer."
4) Set up the Mares Puck 4 and click "Rescan."
5) Now turn on the Puck 4 and go to BLE.
This way, the Puck 4 appears in the Bluetooth list and you can download your dives.