404 Error Pages Returning 200

Hi guys,

i would greatly appreciate it if i could get some direction or help as my host has suddenly stopped with code support and will not help me out with any coding issues.

I created a custom 404 Error page which I uploaded into a folder in Cpanel, along with Css and images etc... and when i go to test it, the custom page is showing as it should, however, the page is returning a 200 instead of a 404Error as tested on https://httpstatus.io/. So after i test a bad page im getting this http://uniqueautoart.com/Error/404.html in the URL

I've put the code ErrorDocument 404 /404/Error/404.html but I'm still cant get it to work. The host seems to think that something in my .htaccess is causing the problem but i'm finding it rather difficult as i am not a coder. I did remove some code from the htacces file which had the custom 404 coming up and sending a 404 code, however, all my pages on my website were then also sending 404.

I'm not sure if it's safe to send all the htaccess code on here but i do have a few 301 redirects on it along with this which i thought might be the problem..

# RewriteBase /store/cart
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !\.(png|gif|ico|swf|jpe?g|js|css)$
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . index.php?sef_rewrite=1 [L,QSA]
RewriteCond %{REQUEST_FILENAME} .*\/catalog\/.*
RewriteCond %{REQUEST_FILENAME} -d
RewriteCond %{REQUEST_FILENAME}/index.html !-f