If you’re using OwnCloud and have a process whereby your add or remove files from directories via some sort of server process, you may find that you need to force OwnCloud to update/rescan the file listing. To do so you can manually run the following command…

sudo -u username php /path/to/owncloud/console.php files:scan --all

You may also want to consider adding it to the crontab for “username” on a daily basis.

Thanks to this site for pointing me in the right direction.