Issue with Redirect Loop

I have a CodeIgniter 3 app that I have been developing on my local machine using WAMP. This includes an .htaccess file to remove the index.php from the URL and everything has been working fine.

I just uploaded it to my hosting account (addon domain configured under cPanel as "/public_html/addondomain.co.uk") and am getting a redirect loop error every time I try to access the home page.

I have removed the .htaccess file, added "index.php" back to the 'index_file' section in the config.php file and have set the base_url to "http://www.addondomain.co.uk".

Whatever I try, I am getting a redirect loop error in Chrome. If I upload a single php file with a simple echo statement it works fine so I am confident the .htaccess at the main domain level (/public_html) is not causing issues.

Can anyone offer any advice?