Hello There,
I have commented the code and it does not affect or display any changes.
<?php
// =============================================================================
// VIEWS/HEADER/BASE.PHP
// -----------------------------------------------------------------------------
// Declares the DOCTYPE for the site, includes the <head>, opens the <body>
// element as well as the .x-root <div> and .x-site <div>.
// =============================================================================
$x_root_atts = x_atts( apply_filters( 'x_root_atts', array( 'id' => 'x-root', 'class' => 'x-root' ) ) );
$x_site_atts = x_atts( apply_filters( 'x_site_atts', array( 'id' => 'x-site', 'class' => 'x-site site' ) ) );
?>
<?php //if ( is_404() ) : ?>
<?php //header("HTTP/1.0 404 Not Found"); ?>
<?php //endif; ?>
<!DOCTYPE html>
<html class="no-js" <?php language_attributes(); ?>>
<head>
<?php wp_head(); ?>
</head>
<body <?php body_class(); ?>>
<div <?php echo $x_root_atts; ?>>
<?php do_action( 'x_before_site_begin' ); ?>
<div <?php echo $x_site_atts; ?>>
<?php do_action( 'x_after_site_begin' ); ?>
I moved my testing in my local testing server and I can confirm that the navigation will not be displayed when you add the base.php file into the child theme. This is a bug in the theme. I have reported this to our developers already.
For the moment, I have renamed the base.php into ++base.php so that this will not take over the and still displays your navigation. We are now back to the issue that error 404 is returning 200.
I will also add this as a bug in the Custom 404 extension so that our developers will be made aware of it and hopefully resolve this in no time.
Thank you for your understanding.