Why can't I see tags in the page source when Tag Assistant says there are tags?

This will happen any time that the client has implemented the Google tag inside of a container tag (such as Google Tag Manager or DoubleClick Floodlight) or an iFrame. Tag Assistant will pick up the tag via the HTTP headers when it fires from within the container/iFrame. However, when you view the page source, all you will find is the container or iFrame as opposed to the Google tag itself.

If you need to find the Google tag, we would recommend using Chrome Developer Tools to identify the tag, request, and initiator. Refer to the Chrome Developer Tools guide and expand the section called 'Steps for Chrome Developer Tools.'