Adding an SSL certificate to my main site breaks my static Addon site
I have shared Linux hosting with a main site in 'public_html', and multiple add-on sites with their own directories within 'public_html' (which is where they are created by default when adding through cPanel).
Everything was working fine until I set up SSL for my main website. My main site is working (WordPress, with 'https://') and all but one of my add-on sites are working (WordPress, non 'https://').
However I have a static add-on site which is now broken: