Garmin sensors when off after a brief stop

Good evening:

It’s the third time that this happens to me: I had to stop for a moment because of the chamois or had to tie my laces, or grab more water…, and the sensors went off and reset everything. And I tried to pedal as much as I could to see if they can recover, but they don’t and I have to drop the training because nothing works again.

I even deleted and added again the sensors and still not working. They show a small spike and die.

What can I do to avoid this when I’m doing a long training?