Creating a bridge between two different pubsub+ instances results in 404.

I have deployed two instances of PubSub+ on separate Kubernetes clusters, both accessible via domain names, and I can successfully log in through the portal. My goal is to connect these instances using a Message VPN bridge. However, when attempting to establish this connection, I encounter a 404 unsuccessful HTTP response.

The Kubernetes pod logs reveal that the URL is being redirected by prepending "/proxy/" to it. Upon examining the image's files, I noticed the following NGINX rewrite rules:

What concerns me is the "return 400;" rule preceding the proxy rewrites. If my understanding of this file is correct, it seems that it will always attempt to return a 400 error before the URL can be correctly rewritten to the desired path.

Both environments are running version 10.9.1.119. Can someone assist with this issue?