This is the testing phase of the SEO tag manager. Once you click the “Preview” button, an orange notification will appear notifying you that you are currently previewing.
Next, open the site that you are tagging, and you should see a “Debug” panel at the bottom of your screen. This panel displays an array of helpful information including tags, triggers, and data layer.
If you look at the left side of the Debug panel, you will see a timeline summary for your event. You should see a minimum of three categories including Page View, DOM Ready, and Window Loaded. If any of these are not visible, there is a problem with your event.