Door senzor disappeared from eWeLink twice!

Hi, I got zigbee door/window senzor on my gate. For second time it completely disappeared from the app with all related scenes.
Not like it would be out of signal. It is just simply nowhere to find in app. In first instance I had pair it again with bridge.
All was working well couple of months since I installed that and now this.
Any advice?

Same here I have to add again every month

I got info from sonoff support. They have re ommended to reset zigbee hub.
I have tried to connect to different and run test as I have more devices on this one.
Do far it works. So next step try factory settibga on original zigbee hub and hope for improvement.
In meanwhile I have bought wifi version. Works like charm. Batteries (2xAAA) lasted two month but we had some really freezing days and it is winter after so I continue to use this. At least for a moment.