sorry for replying late:
there's no cron job involved, maybe that's the issue?
Everything needs to be done manually:
nginx-config whenever Cloudron box is updated, in an SSH session
running the script to start notify_push whenever NC app is restarted, using a terminal from Cloudron UI to access the docker container
after running the start script, and using your ps-check command, I see a corresponding process. Additionally, running <occ notify_push:metrics> in a Cloudron terminal shows it works, all indicated stats are up-to-date and change over time.