I use the following to ‘comment out’ chunks of WordPress pages that I’m still working on
Some old rubbish that I have'nt finished working on yet
This seemed to have ‘stopped working’.
The reason was my ‘Exec-PHP’ plugin was de-activated. I don’t remember de-activating it. I guess it’s possible that an automat(t)ic update might have done so, but I don’t know.