I have two seperate categories with multiple elements. Both the categories and the items in it are published though currently private.

Neither in my admin-account nor in my player-test-account can I see the table of contents on the left side anymore (I was able to see it when I started the project)

I already tried changing the items, categories and the entire world to public but that does not affect the issue.
I also checked if the table of contents is enabled and (as far as I can use that option with the Master Tier) all of them are enabled everywhere.

I can also see in the developer-mode of my browser that the presentation-mode creates the space for the world codex, there are simply no entries in it.

It aalso does not appear to be a browser issue: Same thing happens on firefox and chrome

I have a few custom css lines but even disabling those did not help and changing the theme did nothing either

Is there something I forgot to turn back on?

I do not know how or when it happened or how to reproduce it