re: I am having the same problem and followed the steps on the link above and while they worked they don’t seem to solve my issue.
Yes, it appears your issue is distinct. Looking at your site, you are using a very old version of the cMap template which has been altered (as you mentioned).
This at a basic level is a continuation of this thread from a few years ago.
re: My question is, what code set all the old entries to display as structured lists and why is that not affecting newly created entries. I can say confidently category lists were never manually added even though the lists appear in the entry content block.
Hmmm… looking at the page source, it appears the categories were added manually as an unordered list to the bio field. I say this because the actual category names do not match the categories list in the bio.
This would definitely explain why when you added the code you saw it twice on old entries (once from the manually added list and once from the code you added). This also explains why when you added new entries you do not see the categories… because they were not entered in the bio like the old entries.