Take a view to your MySQL Database > table cron_schedule. There are all magento created jobs with timestamp of creation, scheduled.
crontab> jobs entries, reading their cron_expr elements for detail on how often they should be run. Magento then populates the cron schedule table.
You need to run indexer command to solve this error. From the root of your magento path, php bin/magento indexer:reindex. Check cron is.
Magento depends on proper cron job configuration for many important system functions, including indexing. Failure to set it up properly means Magento won't.
The PHP readiness check doesn't display the PHP version as the following figure If your cron job uses a PHP binary different from the web server plug-in, PHP.
Set up cron for update and upgrade. To enable us to update or upgrade your system, you must have two cron jobs. Each cron job should run every minute.