@chrisherdt, as you can read in your link, this option is not for Splunk to communicate to the outside, but for Splunk 2 Splunk communication through a proxy.  "This process configures Splunk to Splunk communication through a Proxy. The settings documented here do not support interactions outside of Splunk, for example: Access to Splunkbase via Splunk Web Splunk external lookups Actions that make a REST API call to an external service outside of a firewall" ... View more

have you tried changing the FIELDALIAS to use ASNEW (7.2.5 + needed) ? see RN about field alias changes from 7.2 ... View more