I also encountered the issue of cabin passengers disappearing after updating to 3.7.2. I’m using MSFS2020 with the PMDG 737 V3.0.112. Both the front and rear passengers disappear right before entering the aisle toward their seats, just like in the early versions of GSX.
I enabled Show Passengers in the FSDT Installer and set the LOD to 200. Basically, I’ve tried all the publicly suggested solutions, but the passengers still won’t appear.