I have the same problem...
Sony St-Ht5000
Rtx 2080 ti
9900k
Dolby Atmos for home theater worked ar first, then stopped.
I have been able to get it working twice by following some tips from this post, but this time it won’t work.
This is so annoying, frustrating and, well, just pisses me off.
Are we getting a fix for this, MS (or Nvidia or Dolby, I don’t care who fixes ir, just do it!)