I have had a similar problem 3-4 times the last few weeks, mostly in group rides. All the sudden the rider (me) pulls over and stops. I have the H3 Saris trainer and Garmin strap. I just hop off the trainer and unplug the power cable at the trainer, plug it back in and start pedaling and I start going again. This won’t help for a race if you are in the mix but may work to finish the event. It happened Saturday in the long climbing race near the end but at the point it did not alter my finish place, just lost a few seconds.
I did get booted out completely once the software prompted me to continue the interrupted ride and I selected yes, then my cartoon image went way up the air, over a canyon (like ET) and I was on my own riding. It was funny to watch and go huummm…
I only got a partial ride when I saved, but did not care since it was a group ride and I was doing an easy effort.
I thought it was the number of people using the product right now sine nothing else has changed.