Of course, you can insert, delete and reinsert TOC at any time when working with a document. Sorry, I meant “usually you can,” but not today.
I am afraid that even the installation of AOO will not be very successful. Perhaps everything will turn out, I hope so.
While transferring your screenshots to the question, I noticed that all the menus lacked just the last few items. Not from the middle, not from the beginning, namely the “tail” of long menus.
Let’s see if the Windows settings prevent you from working. I have already seen reports that certain desktop themes caused problems with the display of some controls (including the menu)