Setting up the Magento cronjob (Magento 2)
This is a guide for Magento 2. For Magento 1 extensions and guides, please refer to Magento 1 Guides.
Please refer to the official Magento 2 documentation on how to set up the Magento cronjob: http://devdocs.magento.com/guides/v2.2/config-guide/cli/config-cli-subcommands-cron.html
If you are 100% sure that the Magento cronjob has been set up properly, you can try to check the "cron_schedule" table in the Magento database and look for "xtento_" cronjobs that have status "pending". Try deleting those rows from the table and then wait 15-30 minutes for the cron schedule to be regenerated.