I've installed Portal for ArcGIS Server 10.4.1 and added a CA certificate to it, the portal is working very well and can consume https services from ArcGIS Server. However, when I try to add non-https services, it fails to load them and the unsafe content icon appears, so I need to click it in order to proceed.
Is there a way to enable mixed-services mode (http & https)?
Notes:
- "Allow Access to the Portal through https only" is UNCHECCKED
- "Allow anonymus access to your portal" is UNCHECKED

The Unsafe Content icon after adding http layer:

Any help is highly appreciated
Thank you in advance
Hani