Hey Faisal Waheed ,
Could you please check your Windows Proxy Settings - once Fiddler Everywhere is stated and Capturing is enabled, your Proxy settings should be set to Manual with the Fiddler Everywhere proxy set (default 127.0.0.1 with port 8866)? If you do not see this, check if your OS user has administrative rights to change the proxy settings.
Alternatively, you could send us the Fiddler log files so that we could investigate your case further.
I am using the trial version of Fiddler. But Fiddler is not capturing the traffic. Please see the screenshot. I am opening google.com website in Chrome, Internet explorer and Edge but no luck ☹