Browsers have taken to hiding insecure content from viewers when a page is loaded that has content coming from both secure (Moodle) and insecure sources (http rather than https). Unfortunately they tend to do this without informing the user that they have done so. The issue can be resolved by unblocking the content. 

For Chrome: 

  1. Click on the shield in the right hand side of the URL text box (see image below).
  2. Then click on Site Settings.
    Location of the Site settings option
  3. A list of permissions is displayed in a new browser tab. Find the Insecure content permission and change to Allow.
  4. Close the Settings tab to return to the original web page. A Reload button should appear at the top of the page. Click on this to refresh the web page and display the insecure content.
Note: Checked in August 2023 on Chrome Version 115.0.5790.110 (Official Build) (32-bit) - older and subsequent browser versions may work differently.