I had that same problem last night. For some reason, the phone and the tracker were no longer paired. I turned off my phone and restarted it. I reset the tracker with the charger reset button. I was unable to pair them again. Very frustrating. While trying to pair the devices, I did not get to the point of the tracker displaying a four digit code. My phone seemed to be making no progress with pairing either.
Suddenly, several hours later, without trying to re-pair them, the phone app started to sync with the tracker and it showed as 'paired' again.
It seems to be working today, but I have no idea why. I presume you have reset/powered off everything, and then tried to re-pair your devices, so I don't know what else to offer you as far as a solution is concerned. I am assuming the error was with my phone, and not the tracker.
