If you are having problems determining why your Certification Paths are not visible in the front end then you should go to the Certification Paths manager in the admin area.
Mouseover the Warning message and you will see our hidden diagnostics checker.
This image tells me that there is a lesson unpublished.
So, lets go to lesson manager and see it's configuration.
Select the lesson in question and click the configure button.
This will take you to the configure page.
As you can see here, When creating the lesson itself, the option to Make the exam visible was not selected.
This is the option for publishing the Lesson itself.
Check the Option and Save.
Now in the Certification Paths Manager, we can see the Certification Path is Visible in the front of the site.