I have 3 BGP paths to my headquarters. When I look at the path via a looking glass site, only the primary shows up. THe ones I have prepended don't show up..Did I misconfigure something or do the prepended networks not show up?
a looking glass offers a specific point of view over the internet.
Different looking glass can provide different results.
Notice that if none of the ISP receiving your prepended paths has a direct eBGP session with the looking glass this will explain what you see.
You should go on the looking glass of the provider that receives your prepended paths to verify if it accepts them.
Also be aware that if you have three BGP sessions with the same provider it is correct that in the internet you will see only the non-prepended best path.
If you are connecting to different ISPs and they accept prepending you should find the prepended paths at least on the provider's looking glass (if any)
A good source of looking glasses is:
Hope to help