Permalinks stopped working

Hello.

The permalink for the custom content type suddenly stopped working.

My “register_post_type” call looks this:

$args = array(
	'labels' => $labels,
	'public' => true,
	'show_ui' => true,
	'menu_position' => 5,
	'_builtin' => false,
	'_edit_link' => 'post.php?post=%d',
	'capability_type' => 'post',
	'hierarchical' => false,
	'rewrite' => array("slug" => "musterpark"),
	'supports' => array('title')
);

register_post_type( 'musterpark' , $args );

It has worked before and no major changes have been made ever since. Whenever I try to access a “musterpark”-entry via “/musterpark/title-goes-here” WordPress throws a 404.

Accessing the entry via “/?musterpark=title-goes-here” works fine. What gives?

I’ve already deleted the .htaccess file and generated a new one but it still doesn’t work. The actual permalink settings don’t seem to matter either as changing them has no positive effect.

Any help would be gladly appreciated.

Thanks.