Figured out my remaining smaller-than-expected playlist issue.

In PlaylistDevice.py function __add_item_to_playlist, there is a check for "if (count[0] >= 500): return". It appears to be some sort of anti-infinite-loop check. The arrangement of directories and files meant that after skipping directories and adding 445 files, this check passed and adding stopped. I bumped it up to 5000, ran again, and saw a playlist more like I expected .