Theme customizer section vanishes if code is inside is_admin() block

[Latz]

Theme customizer: If I surround the add_section() and add_setting() functions with an is_admin() condition, the new section is not displayed. If I remove the is_admin() condition, everything works fine.

WordPress 4.0 didn't show this behaviour.

I've added s screencast and an example plugin to illustrate the problem.

[Latz]

Example plugin

[westonruter]

I think wrapping the add_section call in is_admin is incorrect anyway. The call merely should be done inside of the customize_register action. Since the Customizer preview executes in a frontend context, any calls wrapped by is_admin aren't going to fire regardless. This means your settings aren't getting registered in the preview either. It doesn't matter for settings though, since they get synced into the preview once the Customizer preview loads anyway. But sections can now be contextual to specific URLs, and for this to work the add_section mustn't be conditional upon is_admin.

[Fab1en]

I have the same issue because I include the customizer files in my theme only if is_admin :

if(is_admin()) {
    require_once(dirname(__FILE__).'/customizer/title/register.php');
    require_once(dirname(__FILE__).'/customizer/background_gradient/register.php');
    require_once(dirname(__FILE__).'/customizer/post/register.php');
}

If that is a bad practice, it should be mentionned in ​the Codex.

This was also very hard to debug because controls are added to the customizer panels, but hidden later with JavaScript.

[Latz]

As mentioned above it's a new behavior since 4.1. I'm going to add a note as soon as 4.1 is public.

[westonruter]

I've updated the Codex with the note: ​http://codex.wordpress.org/Theme_Customization_API#Developing_for_the_Theme_Customizer

It's a best practice already to not wrap Customizer logic in is_admin().