Failed to save page and install apps on design.xwiki.org

Failed to create a page with template. On multiple presses of the save button, the error message reports that the save failed, although the page was created successfully.

Apparently we have a partial configuration for the HTTPS. JavaScript is failing to report the creation job status, because it's using a HTTP URL for the job status, instead of HTTPS (words by enygma).

• Page: https://design.xwiki.org/xwiki/bin/edit/Proposal/Notifications11x/Notifications11xInitial/WebHome?template=ProposalCode.ProposalTemplate&parent=Proposal.Notifications11x.WebHome&title=Notifications11xInitial

• Error:
  Failed to save the page. Reason: Server not responding

• Console:

  Mixed Content: The page at 'https://design.xwiki.org/xwiki/bin/edit/Proposal/Notifications11x/Notifications11xInitial/WebHome?template=ProposalCode.ProposalTemplate&parent=Proposal.Notifications11x.WebHome&title=Notifications11xInitial' was loaded over HTTPS, but requested an insecure XMLHttpRequest endpoint 'http://design.xwiki.org/xwiki/rest/jobstatus/refactoring/create/1550679390925-743?media=json'. This request has been blocked; the content must be served over HTTPS.