Ran into the same thing today. I Tried everything to fix it from updating iPhone 15 and Roku tv. Was going to try to screen mirror it to tv because it plays fine on iPhone. After update on Roku tv screen mirroring stopped working. So the last thing I tried after the usb to c connection straight to the tv wouldn’t work was playing the app through my PS5 and now I can watch through the system and the app works fine. Very frustrating but if anyone is still looking for a quick fix and has a PS5 on hand, I hope this helps.
