To be slightly more technical, the sensor itself loses its connection to the hub and instead of reconnecting it enters pairing mode with the flashing red light to indicate it's ready to pair

I suspect the sensor is unable to reconnect when its connection is lost and it enters pairing mode by default

I even tried this in Home Assistant with Nortek Zwave/Zigbee hub, connects and then loses connection.

Easy native smartthings connection, ok battery life so far.

Keeps losing connection to the hub

None of them have ever disconnected or lost connection from either SmartThings or Hubitat.

They can lose connection at times but will get rediscovered eventually

Ultimately for $15 each, these are great little O/C + Temp sensors

For the price and the for the positives I have learned to live with the.

Ultimately for $15 each, these are great little O/C + Temp sensors