Devices stop sending messages

I have several original Multi Purpose sensors which stopped sending messages to the platform. This happens randomly and without any warning or notification.
If I look in the apps device shows full functionality while they dont work
Device Health is turned on - nothing is notified.
Only way to reconnect is to unmount and mount battery.

Advise or ideas ?

I had a couple of the original SmartSense Multi’s stop as well, and I had to completely remove/delete the device from ST and then reinclude them as if they were new. After I did that they started working again. I also made sure the DTH it’s using was called “SmartSense Multi”, not “SmartSense Multi Sensor”