That would be a mixed content issue.
Mixed content errors mean that your website is being loaded over HTTPS but some of the resources are being loaded over HTTP. To fix this you will need to edit your source code and change all resources to load over a relative path, or directly over HTTPS.
For example, if you load your images with a full URL:
<img src="http://example.com/image.jpg" />
You would want to change this to:
<img src="//example.com/image.jpg" />
By removing the
See this Community Tip for further details
PS: I would not use a Page Rule for the HTTP to HTTPS redirect, there is a toggle “Always Use HTTP” in the SSL/TLS page.