Avatar still moving without my pedaling input

Elite Suito trainer & Zwift via windows 10 laptop.
During a climb of Alpe du Zwift, my avatar stopped at 370m although I was still pedaling hard. After 20 ish seconds my avatar started again, but stayed at 173 watts. No matter how hard or soft I pedaled. I stopped pedaling after I reached the summit. But my avatar continued at 173 watts. Therefore, it seems that my climb up the Alpe du Zwift would have been recorded even if I was sitting on the sofa watching the Giro. In fact, my avatar continued the loop back down the mountain. So, I made a U-turn while stood by my laptop and the avatar continued back up the climb. This issue appears to be fixed after re-start up of the Zwift program. . . . But it may happen again. Has anyone else had this strange issue?