407 means that MWG wants this request authenticated. Typically for NTLM Authentication you may have up to two lines with 407 before there is a line with a status code of 200.
Can you verify there are requests to the same URL which do not have a 407 as a status code in the access.log? If there are some there is a different issue apart from authentication. If all are answered with 407 the application is most likely not able to authenticate, or is not configured to authenticate. In this case you could check whether you can specify username/passwort for the proxy somewhere in the application, or exclude the URL from your authentication rule set and see if this helps.
Thanks for that. we have added the website to the Authentication whitelist, so it will not request authentication and also added the site to an application authentication whitelist we have created. The software can now access the required services without any issues.