Edit Premiere sequence in Audition mutes most tracks

Mac OS 11.3.1. 2020 iMac, 3.6 GHz 10-Core Intel Core i9, AMD Radeon Pro 5700 XT 16 GB

I'm on the latest release  of Premiere (and Audition), but my problem predates it.

I have a project that won't seem to link properly to Audition for editing. When I send it to Audition the session file only plays back one track..the meters seem to move but I hear nothing, The project audio does play in Premiere.

I've copied the clips to a new sequence and recreated the audio setup and, and I've tried  importing the sequence into a new project. The problem persists.

A project with a similar setup does work as expected in Audition.

What am I missing?

And, BTW, is it normal for track 1 and the mix track to return to the "touch" state, even after I switch them to read? I hadn't noticed that behavior before.

I've attached screen shots from a functional project, and the non-functional one.