The FiddlerCore Proxy works in the same way that the Fiddler Desktop Proxy works. In order for FiddlerCore to work with this configuration it will require chaining to the upstream proxy. See the configuration article for how to do this in the Startup class.
Additionally, if you set Chrome to the upstream proxy this will bypass the FiddlerCore configuration and traffic will not be captured. You will likely need to set the Chrome proxy to the FiddlerCore endpoint.
Please give this a try and let me know the results. Thank you for using the FiddlerCore forums.
Eric R | Senior Technical Support Engineer
Progress is here for your business, like always. Read more
about the measures we are taking to ensure business continuity and help fight the COVID-19 pandemic.
Our thoughts here at Progress are with those affected by the outbreak.