I have Dexcom but have had issues with it not reporting data. The support line is good but other than sending me replacement transmitters and sensors they haven't permanently fixed the issue.
One of the issues has been that if your phone updates itself it can knock certain settings out like GPS location, power saving mode (needs to be OFF) and you musn't let the battery run down low. The helpline guys will talk you through these things but get it done soon as they don't support at the weekend.
Would wearing the sensor on your stomach help keep it in closer contact with your phone (if you carry the phone in a pocket).
It seems to go out of blue tooth range quite often and eventually I was advised not to use Clarity or the app because it was stopping the comms with my pump which auto corrects my dose still. It now talks to the pump and I have stopped compulsively checking my phone every 5 minutes!