Using the modifications to apcu.ini described above, I was able to trigger a scan (as root su’ing as nextcloud, but not as admin.)
Seems like this documentation needs to updated:
Near the section where it asks one to scan.
I would do it - but I still got an error: “Home storage for user x not writable Make sure you’re running the scan command only as the user the web server runs as” for most of my users - not sure why.