Yes, first thing was to check firmware before using. I keep up with firmware on my Garmin devices, usually updating as soon as they come out.
One other issue in my case may be temperature. The disconnect happened at 29 degrees F, just as the sun went down and temperatures dipped below freezing. I have had Garmin cadence sensors disconnect in the cold, though those are coin cell battery powered, not USB. I still had 75% battery left on the Varia when I ended the ride.