APM Portal Access - Teamforge/cache-fm.js Troubleshooting Suggestions

Have an EdgeGateway running 11.6.2HF1. We are using APM/Portal Access to expose a Teamforge instance to customers. The issue is that the Teamforge server was just upgraded to the latest version. The previous version worked while the new version fails to display even the initial login page. It is downloading everything it seems (firefox dev console) yet it fails with a 400 error or "Bad Request Your browser sent a request that this server could not understand" The error seems to be related to cache-fm.js from the EdgeGateway. Some kind of incompatibility. Unfortunately, the consoles in firefox nor opera show an actual error nor point to the specific function within cache-fm.js. So this post is to ask for suggestions of additional troubleshooting methods to try to narrow down the issue further.

Thanks in advance!

-Mark