Cron is a technical term used for commands to run on scheduled time or at regular intervals. Similarly, WordPress has an in-built WP Cron to perform scheduled tasks.
Upsell is also dependent on WP Cron to perform specific tasks. Therefore it's necessary that WP Cron must be working.
We can easily detect whether WP cron is working or not on our site by performing the simple steps below without using any plugin
Step 1: Add a new page
Navigate to WordPress Dashboard > Pages and click on Add New Page.
Step 2: Schedule your page for a future date
Add any title or content to your page. Now click on Publish settings to assign a future date.
Next, schedule the page for that time.
In the previous step, refresh the page after the set time.
If the page gets published, it means WP Cron is correctly working.