Downloaded Severance, found that one episode downloaded audio as AAC HE instead of the selected ATMOS, went back to play that specific episode on ATV then got SF to analyse it (luckily SF analyses the “continue playing” episode), and the correct audio track (ATMOS) was selectable and downloaded this time…
Sounds like the same as DoVi/HDR10+/SDR selection mess again but applied to audio.
Edit: spoke too soon, investigating…