Bingo! I managed to sort this on my server.In my case I have nginx running, but I disabled "Smart static files processing" and now this osTicket function works as expected.It doesn't quite make sense to me that this would be the fix, as the Site Pages are certainly not 'static' (perhaps a wiser mind can explain this)... but alas my tech life is never short on unsolved mysteries.Hope this helps someone, somewhere, someday.