I think I’ve solved the issue now.
I have a 3rd party javaScript contact form on all my pages that changes from time to time so I use shortcoder so I can update all my pages from one place.
One of my sites is getting the words ‘No sqn given’ instead of the contact form.
I have it set up on over 10 other site’s and they are working fine.
The funny thing is that it works fine when i’m logged in to WordPress, but as soon as I log out I get the ‘No sqn given’ error and so does everyone else visiting the website.