Alternatively, you could also use the special alias set by Fiddler which is ipv4.fiddler or ipv6.fiddler (if using IPv6) instead of localhost. More details on why this alias is needed is posted this article for the classic Fiddler (which uses the same technique).
I just replied to the support email that you submitted, but I want to share the information here as well, so anyone facing this issue can get an answer more quickly.
I have an outlook add-in and I am trying to monitor traffic from a local daemon (http://127.0.0.1:4002). So from my Outlook Add-in I am making a request to the local server running on my machine. Is there anyway to monitor this traffic?