I was pleasantly surprised that the HDR option worked well the first time I switched it on. The picture absolutely became HDR and the HDR symbol indicating it was on appeared on my TV.
However, after we changed channels, when we changed back to the Linux PC the TV claimed that it couldn’t receive a signal. So, I connected to it via Connections using my Linux laptop and I was able to control it just fine, and switching off HDR instantly restored the signal.
So, I’m able to switch HDR on and watch HDR content, but I need to remember to switch it off before I switch channels on my TV. Where does the blame for this bug lie, I wonder? 