Reckon the .htaccess file is not set as “writable” in your host for user www-data. Do you have access to the terminal (console/command line) of this server by chance?
Access to the cPanel is pretty limited and the business support types, try as they do, find supporting our favourite template difficult. I checked on additional access rights and got rejected. A friend of mine who looks after the Flinder’s Uni Servers has also tried helping but got frustrated with the hosting platform. He asked me,"…If you can sort out SSH access (that is, command line access, not FTP) with ISP, we might have a chance."
Not to worry. The world is full of workarounds. I have a new question so I will start another thread.