I eventually figured this out. It all came down to the Edge Webview2 Runtime that is a pre-req for Citrix Workspace. It turned out we had that installed in several different appstacks and apparently Webview doesn't like that. We fixed this by tearing it out of every appstack we found it in and then installing it on the Master Image and our packaging VM. This way it was always present in case it was a pre-req for anything else.
Once that was done, Citrix rendered fine and we were good to go.
