Doesn't save background

I cannot reproduce this issue on a clean install of the latest version of WordPress. My recommendation would be to deactivate all other plugins and switch to one of the default themes to test.

I don’t think the theme is the culprit. The installation is fresh any way and I don’t have any other plugins.

As mentioned, the metabox is loaded and I noticed in your code it checks that there is no conflict in the variables you used. So if there were to be a conflict, it wouldn’t load the meta box.

I just replaced the php files of your plugin one by one, nothing is fixing the issue.

It is simply not writing to the SQL database.

Here’s the theme support code in Functions.php:

add_theme_support( 'custom-background', array(
		'default-color'			=> 'CECECE',
		'default-image'			=> get_template_directory_uri() . '/images/background.jpg',
		'default-repeat' 		=> 'no-repeat',
		'default-position-x' 	=> 'center',
		'default-position-y' 	=> 'center',
		'default-attachment' 	=> 'fixed',
		'wp-head-callback' 		=> '_custom_background_cb', )
	);