My Roku Express 4k (3940 series) won't play HDR content when connected to my 4k HDR monitor - it definitely did previously.
Also on boot, I get a black screen if it tries to play any video, but not in menus - I have to go to display settings, change to 4k, play a video - at this point I only get the top left ¼ of the content so have to go back again and select 4k HDR again, at which point I can watch content, however it is in 4k, not 4k HDR (even for 4k HDR available content).
I tried going to "advanced display settings" to debug this, and found that even hovering over that entry in the menu crashes the entire system and after around 15-30 seconds it reboots.
I've tried a system reset to fix this, however it hasn't fixed anything, so it seems like either a system update has broken something, or some hardware in the device has failed.
I can still play 4k HDR content using my desktop PC, so it seems unlikely that it is the display or the cable which is causing the issue.
