Cannot Add certain features to XWiki articles or edit Articles that contain any of these features

Many features of XWiki have stopped working for my user-account (which is also an admin account, I have set the XWiki instance up myself)

These features are for instance:

  • tables
  • Display of Code
  • even infoboxes

basically anything that goes beyond the most simple text-formatting and requires some sort of macro.
Whenever I try to edit a page containing any of these (or create a new page with any of these), and I try to save the article i am prompted with

“An authorization error occured when performing this action. Your might have been logged out since you started to edit this page…”

Whenever I click the “Source” button in CKEdit, instead of the XWiki-syntax source of the page, I see
“The service used by the CKEditor source plugin to convert between HTML and wiki syntax.”
Whenever I try to insert

So far, I have only observed this with my own account (everything worked fine for another coworker)

Apparently this happens if and only if I try to access the XWiki via https.
Since this changes the way the question is frramed and i cannot edit the original questino i reposted this here: