hey Richard,

Is it possible pass me with your Cloudflare access so I can better have a look? Because this issue most likely conflict with Cloudflare,

I really can't give you access to my Cloudflare account. However I did a second test and discovered that disabling their feature called Rocket Loader does indeed fix the problem. However it's not a great solution as that means I'm no longer getting the benefit of cached content.

There is another feature to create page rules and it looks like there is an option to bypass the cache for certain files. Can you tell me which file or files are affected? I can create a rule to affect a single file or a URL pattern. See attached image.

Try following how to exclude specific URL from Cloudflare caching and see how it goes.
https://support.cloudflare.com/hc/en-us/articles/200172316-How-do-I-exclude-a-specific-URL-from-CloudFlare-s-caching-
https://support.cloudflare.com/hc/en-us/articles/200168306-Is-there-a-tutorial-for-PageRules-

Exclude these following script folder.
http://yourdomain.com/media/foundry/5.0/scripts
http://yourdomain.com/media/com_easyblog/scripts

Note : You have to purge the cache after you setup.