PHP code showing on user side – hooks broken

Just wanted to share in case it helps anyone. I was having a problem where some php code fragments were displaying in place of the post header and related posts sections, on the front end (user side) of every post on my site. Finally figured out it was due to a setting in the plugin Real Simple Security- I had activated the “Disable the built-in file editors” feature under Settings > Hardening. Apparently that sets DISALLOW_FILE_EDIT to true, causing the problem. As soon as I deactivated that setting, everything went back to normal.