I added the HD trial to my account a few days and it is seems very glitchy to me, nearly all the albums I'm looking at have most of the tracks missing:
e.g this is the new Lumineers album on Amazon (via Bluesound)
Screenshot 2019-09-18 at 18.24.54 by The Biglebowski, on Flickr
You have to click "SHOW ALL" in top right to see all the track.
Problem I have is when using BluOS there is no way to add or edit Amazon music like there is with Tidal. I have already posted same on the Bluesound help page so hopefully this will be sorted with the next software upgrade.