With the latest update of Plex for iOS (4.23.1), I can watch 4K HDR videos cleanly on an iPhone X. The same videos look washed out and lifeless using any browser in a 5K 27" iMac. Any ideas on making that work?
The reason for this is because the PMP is not direct playing your 4K HEVC content, if any PMP transcode 4K content of any kind is going to look washed out. I noticed this few days ago. Download the Plex Media Player for your Mac instead of using the browser and see if your 4K content looks washed out, I have an iMac non 4K and my 4K content looks normal when I play it on the PMP. Make sure all your PMP’s have direct play enabled, but this is not a guaranteed solution since my other devices look washed out as well, Plex needs to look this up. Don’t know if is a file thing.