Hi Mahesh,
Thank you, you were exactly right. I was using Cloudflare to minify CSS. Turning this feature off saw a return to normal function.
However, there is of course a performance loss in doing so. I had been successfully using minify CSS for a long time prior to the recent updates, has there been a change that might have affected this? As noted previously, reverting to a Catch Box version prior to recent updates also corrected the issue. Ideally it would be preferable to have proper function without the performance loss if possible.
Regards,
Matt