Because only products that do have a difference between Amazon and Sellics will show up in Content Monitoring!
If you do not see any of your products in Content Monitoring, it's good news! If the tool is empty it means that all of your live products on Amazon match the content you have saved in Sellics.
For more information about how Content Monitoring works, visit What is Content Monitoring?
For complete guide, visit The Complete Guide to Content & SEO.