Dynamic head tracking

I’m trying out the dynamic head tracking feature of AirPods Pro. While I have no issue selecting spatial audio for supported content, I do seem to have trouble activating dynamic head tracking.

- I can listed in spatial audio through AirPods Pro on Apple TV 4K (1st generation, 2017, tvOS 15.3), but no head tracking.

- I can listed in spatial audio through AirPods Pro on iPhone 12 Mini (2020), with dynamic head tracking.

- I can listed in spatial audio through AirPods Pro on iPad Air (3rd generation, 2019), with dynamic head tracking.

Listen with spatial audio for AirPods and Beats - Apple Support

This support page lists ‘Apple TV 4K with tvOS 15’ as compatible. I did verify that the Center on TV option is on.

Why won’t AirPods Pro allow dynamic head tracking on my Apple TV?