Night before last rented 2023 movie "The Holdovers" on Amazon Prime. The start or any fast-forwarded to part of the movie would play fine for 10-15 seconds and then instantly become what I'll call "multicolored snow" -- a dynamic jumble of tiny rectangles. Only the content of the movie itself was thus obscured; audio continued OK and anything else on the screen, such as fast-forward vignettes at the bottom, also OK. Another (free) movie and a BritBox (Amazon subscription) series that we've been watching played OK. The problem movie also plays OK on the Amazon Prime iPhone app. The next morning, the condition still persisting after rebooting the Roku, I spent an hour(!) on the phone with Amazon support with the only result being to consult Roku support.
Last night, on the assumption that this was an Amazon Prime problem, we rented the same movie on Apple+ with the same disappointing result. I think there was a shorter delay before the video content was lost. Other Apple+ content seemed OK.
I'm mystified. The Roku has been in use for about 1.5 years.
4800X - Roku Ultra; Software v. 12.5.5; connections: Ethernet; HDMI to AVR.
