Fiddler is failing set up the system proxy.
This is what the log says:
11:37:30:6321 Fiddler Running...
11:37:30:6321 Fiddler was unable to get information about the proxy for 'DefaultLAN' [0x2f92].
11:37:30:6321 !WARNING: Failed to get proxy information for Connection 'DefaultLAN'.
11:37:30:6321 Setting upstream gateway to none
11:37:30:6351 Windows 8+ AppContainer isolation feature detected.
I also tried to manually change the proxy settings from inetcpl.cpl. but when I try to click "OK" in the "LAN Settings" dialog, nothing happens. The "Cancel" button does work though.