Thanks for the suggestions. I did all of the above and more working with customer service - one guy in Malaysia

- After a few hours of troubleshooting - they are replacing them as a 1 time courtesy.
These were the steps he suggested -
Kindly follow the below troubleshooting steps:
1) Please ensure while screwing sensor on the valve there is a hissing sound.
2) Before you try to pair please reboot your phone ( switch off and switch on).
3) Try sensor on any other tire and try to pair, this is to confirm there is no blockage in the valve.
4) Don't screw the sensor on the valve until the app guides you to do so.
5) Take out the sensor battery wait for 15 seconds and place it back and try to pair.
6) Please ensure Mobile bluetooth, location service & internet is on.
7) Put your mobile on flight mode and only switch on the Bluetooth then try to pair.
8) Please ensure while pairing your mobile touch the sensor.
9) Delete the current App and download again.
10) Please ensure your mobile battery is not less than 20%.
11) Remove the mobile from casing ( if there is any).
12) Press down the battery cage to create a tighter contact? It's tensile steel, so it will spring back so there is no need to worry about over pressing.