Confluence Connect Javascript API Events not are working in JSM article view with custom domain.

Issue Summary

The Events API is not working in dynamic content macros inside the JSM Article view when the customer has a custom domain.
 
 Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('<URL>') does not match the recipient window's origin ('<URL>').

Steps to Reproduce

1. Setup a Confluence Space as Knowledge Base in a Jira Service Management project
2. Create a custom domain for the Service Portal
3. Install the App
4. Add some language macros on the page, eg. german & english
5. view this page in the Knowledge base view in the Jira Service Management Customer Portal
6. The language macros communicate via the JS event API to identify which language to show

Other responses for window.AP. (based on the test with another app)

undefined

Expected Results

The app should work the same way also from Custom domains. 

Actual Results

Failed to execute ‘postMessage' on 'DOMWindow': The target origin provided ('<URL>') does not match the recipient window's origin ('<URL>'). in the browser console. → the macros don’t show content. happens in the all.js, you can find it in the logs.

Workaround

Use the app from the normal domain (domain.atlassian.net) instead of custom domains.