[Multisite/Domain Mapping] posts get 404 error, permalink issue

Hey guys!

This is my situation:

I am using the Multisite function and WordPress MU Domain Mapping to run 3 wordpress sites in one network.
http://abenteuerwald-thale.de
http://brockensprint.de
http://ski-outdoorschule-schierke.de

While creating new posts on the 2 “sub sites” http://brockensprint.de and http://ski-outdoorschule-schierke.de, it doesn’t work on http://abenteuerwald-thale.de. When I create a new post, I get a 404 page not found error. This does not happen when I don’t publish the post – if I follow the permalink for the draft, it is shown.
Flushing the permalink structure did not help.

As you can see here: my posts are displayed, but when I click the link, this error pops up: http://abenteuerwald-thale.de/archive/459 (page not found)

I need to find a solution so my posts on my main wordpress are found again. Unfortunately I can not domain map this site because it’s blog ID is 1. Could this be the issue?

Do I need to change anything here?

What I also find suspicious is the fact that the URL is not shown as a permalink at all.
(in my other sub wordpress sites the URL is shown as you can see here:

)

This 404 error only occurs on blog posts. On pages everything is displayed correctly.

My htaccess is as suggested by the network setup:

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]

and the changed part of the wp-config.php

`define(‘WP_ALLOW_MULTISITE’, true);
define(‘MULTISITE’, true);
define(‘SUBDOMAIN_INSTALL’, false);
define(‘DOMAIN_CURRENT_SITE’, ‘abenteuerwald-thale.de’);
define(‘PATH_CURRENT_SITE’, ‘/’);
define(‘SITE_ID_CURRENT_SITE’, 1);
define(‘BLOG_ID_CURRENT_SITE’, 1);
define( ‘SUNRISE’, ‘on’ );
define(‘COOKIE_DOMAIN’, false);

What can I do to get the posts back to work?