I have an issue with hdr too on my Toshiba TV, I have to keep mine in always Dolby Vision, if I change to always HDR or match content the colours get messed up and there's either a strong purple or green tint all over the screen
Yeah HDR isn't working on mine as well after the latest update. I first thought it was the Apple TV app but tested it on others and didn't worked tried with the TV apps and it worked.
If there was any major issue with Samsung TVs, this sub would be swamped with complains like this.
Do you mean you are having trouble with HDR on the Chromecast with Google TV?