Screen cast from iPhone to Roku doesn't show video in Sufferfest

Screen cast from iPhone to Roku doesn’t show video in Sufferfest workouts. iPhone 7Plus with software version 15.1, KICKR Bike, Roku Streambar with software version 10.5.0.4201.
It will show power, cadence, speed and workout progress but not the video part. I’ve tried casting it directly from my phone and also using the Mirror for Roku app; neither will show the video. Any advice?