I have definitely done the Plex dance. I tried some manual scans, but didn’t see anything interesting there… Any in any case, it doesn’t LOOK like scanning is fundamentally the problem, as the logs show the scan working okay.
I’m very curious what the conditions are for the Sonic Analysis features to be displayed. I created a new “test” library and left Sonic Analysis off from the beginning. The Sonic Adventure tab here will let me pick things from other libraries, but when I create my mix it warns me that I have no analysis data and just queues up the two tracks.