Cron jobs are not running

Hello,

I am having issues where the cron job will not run (according to the admin - basic settings page it last ran 8 days ago)
I am running the latest docker NextCloudPi image on a Pi 4.
Iā€™ve seen in the docs that the ā€˜www-dataā€™ user needs to execute the cron.php file. Iā€™ve confirmed that it exists in the crontab by opening a shell in the NCP container and when I manually run it, nothing happens.
Besides the alert displayed on the admin-basic settings page, I havenā€™t noticed any other issues so Iā€™m not sure if this is actually an issue.

Should I be creating the cron job on the actual hostā€™s crontab instead of the container?
Iā€™ve copied my NCP docker configs below for reference.
Hereā€™s where the default cronjob was set up.

XXX:~/MyFiles/docker]$ docker exec -it nextcloudpi bash
root@af950bcffb9e:/# crontab -u www-data -l
*/15 * * * * php -f /var/www/nextcloud/cron.php
root@af950bcffb9e:/#

Let me know if I should have included any more info!

NextCloud - Self-hosted storage

nextcloudpi:
container_name: nextcloudpi
image: ownyourbits/nextcloudpi-armhf
networks:
- t2_proxy # This is for traefik
environment:
TZ: $TZ
ports:
# - ā€œ80:80ā€
# - ā€œ443:443ā€
- ā€œ4444:4443ā€ # for the admin page
volumes:
- $MAINDIR/nextcloud/data:/data
- $MAINDIR/nextcloud/etc-localtime:/etc/localltime:ro
restart: unless-stopped