scanning doesn't see mu Samsung phone A8

There is a (confusing) difference between standard Bluetooth and Bluetooth LE.

Most phones will advertise on Bluetooth but may not advertise on Bluetooth LE by default. You could try installing nRF Connect as suggested above.

On my phone:

• NRF.findDevices(print) does not properly list the phone
  
• Start nRF Connect, go to 'Advertiser', add a new advertise type and turn it on
  
• NRF.findDevices(print) now shows the phone
  
• If I turn 'Advertiser' off the phone is no longer visible on Bluetooth LE