Thanks for the note here.
I just tried testing this on the same model of device, and am seeing 4K HDR playback. A few things you can do:
1. When you are on a movie/tv show details/description page, prior to starting to play the title, press the * key on your remote. This will enable additional streaming stats that will display in the upper lefthand corner of the screen during playback. This will show you the current stream that is being delivered to your device.
2. Ensure the content title you are trying to play is offered in 4K HDR. The HDR badge should appear on the details/description page. 'Stranger Things' and 'Chilling Adventures of Sabrina' are both Netflix original titles that should be available in 4K HDR.
3. Double check that your home network connection is providing adequate bandwidth to stream 4K HDR content. (I believe Netflix recommends a minimum of 15MBPS for this quality.) You might try restarting your internet modem and wireless router, as well as your Roku device, to see if this helps clear things up.
If you visit Settings>Display type on your device, what display resolution is showing as detected? (Bottom lefthand corner) Have you tried changing this manually to 4K HDR 30Hz or 60Hz to see if this helps resolve the issue?
If that still isn't doing the trick, I'd recommend contacting Netflix support to report the issue. Although less likely, it's possible that they are encountering a content delivery network issue that is preventing an HDR quality stream from being delivered to your device, etc. You might also contact your ISP to see if they have any additional insights to share based on what they can see from your internet connection.
Keep us posted if you need any additional help from there!
Thanks for your reply.
So my auto detect display type is 4K HDR 30Hz. I manually changed the display type to 4K 60Hz (no HDR) and the Ultra HD 4K labels reappeared with the streaming stats confirming it was 4K playback.
However as you can probably guess, the HDR labels were then gone. I changed my display type back to 4K HDR 30Hz and the HDR labels returned while the Ultra HD 4K labels were gone again. The streaming stats showed 1080p playback.
It is seemingly making me choose between 4K or HDR but it won’t give me both even though my TV certainly supports it. This is very frustrating.