.htaccess rewrite path: New query string removes the paths first trailing slash - apache

Question

I have this code to rewrite a path, and then redirect to subdomain's folder:
RewriteEngine On
RewriteBase /
RewriteRule ^category/?$ category.php
RewriteRule ^category/[a-z0-9\-]+\_([A-Z0-9\_]+)/?$ articles.php?id=$1&section=category
RewriteCond %{HTTP_HOST} ^test.(.*)example.com/?$ [NC]
RewriteCond %{REQUEST_URI} !^/\!test/ [NC]
RewriteRule (.*) /!test/$1 [L,NC]
RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [NE,L,R=301]
The big problem is that typing this in the browser address field and press Enter:
http://test.example.com/category/article-about-something_35436
Ends up in that it changes by itself to:
http://test.example.comcategory/article-about-something_35436
And the browser of course tells you that "Server is not found".
Troubleshooting
I have figured out that this works fine:
http://test.example.com/category
And removing the query string ?id=$1&section=category from the second rewrite rule works. You don't end up on the article of course but on articles.php.
So, anyone know the problem?

Answer 1

Rearrange your rules and keep redirect rules with R flag before other internal rewrite rules:
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} ^example\.com$ [NC]
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [NE,L,R=301]
RewriteRule ^category/?$ category.php [L,NC]
RewriteRule ^category/[a-z0-9-]+_([A-Z0-9_]+)/?$ articles.php?id=$1&section=category [L,QSA]
RewriteCond %{HTTP_HOST} ^test\.(.*)example\.com$ [NC]
RewriteCond %{REQUEST_URI} !^/\!test/ [NC]
RewriteRule (.*) /!test/$1 [L,NC]