Hi
Did you set up Burp to redirect outbound traffic? You can find out more information about this under "Redirecting outbound requests" here:
https://portswigger.net/burp/documentation/desktop/tools/proxy/options/invisibleWithout setting this up, Burp will resolve the hostname to your listener address, and unless configured differently will forward the request back to itself, creating an infinite loop. As your connection is hanging and not opening, this sounds like it may be the cause of the issue.
Alternatively, "Intercept" may still be enabled on your Burp installation. You can check this by going to "Proxy > Intercept" and making sure that intercept is turned off, or that you forward any requests that come through Burp.
Have you tried modifying your hosts file instead of using iptables, like in the documentation? If you are having issues getting proxy listeners to bind to ports 80 and 443, you will need to launch Burp using sudo.