Rewrite_rule issue cms admin not working 404 error

After i move from Apache to OLS
website is running fine but cms admin is showing 404 error from frontend website.

i got two seprate .htacess file one for website and another one for cms admin (/backend)

backend/.htacess is not working

website .htaccess file
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^/index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

cms admin website_path/backend/.htaccess
RewriteEngine on

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d

RewriteRule . index.php
I had a similar problem, where .htaccess rules would work only for some directories.
By comparing them, I figured out that I need to set an empty Rewrite Context in Virtual host for each directory that contains a .htaccess file.
So in your case, you can try to create an empty context with URI website_path/backend/, save it and reload the litespeed server.

It took me a lot of time to figure this one out :)