Ride power dropping out

Very shortly after starting a ride the wattage goes to zero and I’m just spinning the pedals while the video starts creeping but the HUD still shows cadence and speed as up. Totally dysfunctional. Tried the new app on my iPhone and then on my wife’s iPhone with the same result. Started a free trial with Rouvy just to see if it was my trainer, but everything is working just fine on Rouvy.