Why can I not watch an hdr YouTube video at 4k on my Xbox 1 S?

I recently got a 4k tv and have been using it with my xbox 1 S and I was wanted to watch some hdr video on it. I noticed that on youtube, I can't select an hdr video resolution of more than 1440p. I can select 4k when a video is not hdr, but when it is hdr, it doesn't seem to allow it.

Does anyone know why? I bought an hdmi 2.1 cable specially to avoid this problem, so I'm not sure what could be going on other than a software thing. Is there another app I can check to see if it is the cable or just Youtube? Netflix, (hbo) max, and hulu all don't give me the option to select a resolution. Although they do pop up the hdr10/dolby vision logo when appropriate.

I'm 99% sure it should be able to handle it since the ports are hdmi 2.0a, but at this point I'm stumped.

:)