Issue Summary

While a custom domain is enabled for Confluence Cloud product, the Import from Google Docs does not work.

Instead of logging in to the respective Google Account, we receive an error message: 

Steps to Reproduce

1. Enable a custom domain for your Confluence site
2. Create a new page draft
3. Click "..." (More Actions) > Templates & import doc
4. Select the tab "Import" and pick "Google Docs"
5. Click "Sign in with Google"

Expected Results

Prompted to login into Google Account

Actual Results

Error message:

{"error":{"code":"FORBIDDEN","message":"Invalid origin"}} 

Workaround

Currently, the only known workaround is temp disabling the Custom Domain to perform the desired import and re-enabling it afterwards.