SOLVED: DV file / HDR issues on supported device

[podonnell]

The video is transcoding because the player doesn't support HDR even if your TV/OS/monitor does.

Tone mapping is likely not a viable option for your hardware anyway.

I'm confused, because this player works for HDR on plenty of other files.
I think there is something specific about this format / container. How can I determine what exactly about this one is not supported?