Not Acceptable!
An appropriate representation of the requested resource could not be found on this server. This error was generated by Mod_Security.

It seems like this error generated by Mod_security, can you consult with your webhosting provider regarding this and see how it goes? It probably because of that mod_security false alarm, it would be best to turn it off temporary and see whether all the issue will resolve?

If the issue still persists, can you update your site backend and FTP access at https://stackideas.com/dashboard/site so we can better have a check?