I’m not getting the 404s anymore or the Token mismatch error, so that’s great.
However, if I add an entry then submit the form, when the page refreshes, I get an “Add directory” link on the menu rather than an “Edit directory link”. I was able to add multiple entries this way, which isn’t ideal! The correct link appears on other pages however, and on the form page when I log back in. The caching plugin isn’t enabled, so it’s not that.