I just thought i would add to thi ticket after a bit of testing!
I now have it working!!
I had all the settings correct and tested turning off plugins etc.. but that did not work.
But what i have found is the site used WP Rocket and it looks like the new version with its auto update of the settings was causing an issue with not refreshing the setting until i did a full cache flush and this seems to need doing after every minor change, so im not sure if its the way the new plugin does the auto save or a WP Rocket one as i never remeber the issue with the old version that had the manual save button.
Please mark this as resolved.
Thanks
Andy