Burger menu not loads menu items

Hello Kieresi Team!

My burger menu is just an empty page and has no menu items in it.

I have some modifications in my theme’s functions.php and some CSS rules @ my child theme.

What am I tried?
Disable plugins -> Not working
Switch to parent theme -> Burger menu works
Child theme with basic functions.php -> Not working
Child theme without custom CSS rules -> Not working
Custom rules in parent theme’s custom.css -> Burger menu works
Cache basically disabled, but erased many times -> Still not working
Compared my HTML output with Enfold 2017 demo and seems my burger menu not loads menu items. The #av-burger-menu-ul is empty in my case
The site is here: http://195.201.1.25/

I don’t know it’s related or not but I’m added support in CSS for iPhones but iDevices not renders my Child Theme’s CSS.

Here is my functions.php:

<?php

/*
* Add your own functions here. You can also copy some of the theme functions into this file. 
* WordPress will use those functions instead of the original functions then.
*/

//Remove query strings
function _remove_script_version( $src ){ 
$parts = explode( '?', $src ); 	
return $parts[0]; 
} 
add_filter( 'script_loader_src', '_remove_script_version', 15, 1 ); 
add_filter( 'style_loader_src', '_remove_script_version', 15, 1 );

//Extra fonts
add_filter( 'avf_google_heading_font',  'avia_add_heading_font');
function avia_add_heading_font($fonts)
{
$fonts['Robot Slab'] = 'Roboto Slab:400,400italic';
return $fonts;
}

add_filter( 'avf_google_content_font',  'avia_add_content_font');
function avia_add_content_font($fonts)
{
$fonts['Roboto'] = 'Roboto:100,300,400,400italic,500,700,900';
return $fonts;
}

//Search form shortcode
function bigfootsearchform( $form ) {
 
    $form = '<form role="search" method="get" target="self_" id="searchform" action="' . home_url( '/' ) . '" >
    <div>
    <input type="text" class="search-text" placeholder="Keresés" value="' . get_search_query() . '" name="s" id="s" />
    </div>
    </form>';
 
    return $form;
}
 
add_shortcode('bigfootsearch', 'bigfootsearchform');

// Function that will return our WordPress menu
function menu_function($atts, $content = null)
{
	extract(shortcode_atts(array(
		'name' => null,
	) , $atts));
	return wp_nav_menu(array(
		'menu' => $name,
		'echo' => false
	));
}

// Create the shortcode
add_shortcode('menu', 'menu_function');

//Register new sidebars
function arphabet_widgets_init() {

	register_sidebar( array(
		'name'          => 'Footer Big Socket',
		'id'            => 'footer-big-socket',
		'before_widget' => '<div>',
		'after_widget'  => '</div>',
		'before_title'  => '<h3 class="widgettitle">',
		'after_title'   => '</h3>',
	) );

}
add_action( 'widgets_init', 'arphabet_widgets_init' );

//Change logo on scroll when transparent header enabled
add_filter('avf_logo_subtext', 'kriesi_logo_addition');
function kriesi_logo_addition($sub) {
    $sub .= '<img src="/wp-content/uploads/2018/02/dandy-logo-edited-secondary-res.png"/>';
    return $sub;
}

//Hide header on scroll
function add_hide_header(){
?>
<script>
jQuery(window).scroll(function(){
if(jQuery(this).scrollTop() > 200) jQuery('#top #header_meta').fadeOut('1000');
if(jQuery(this).scrollTop() < 200) jQuery('#top #header_meta').fadeIn('1000');
});
</script>
<?php
}
add_action('wp_footer', 'add_hide_header');

// header transparency logo switch
function add_custom_script(){
?>
<script>
(function($){
	var win = $(window);
	win.scroll(function() {
		if(win.scrollTop() == 0) {
			$(".av_header_top:not('av_header_transparency') .logo img").css('display', 'block').css('ease-in', '0.9s');
			$(".av_header_top:not('av_header_transparency') .subtext img , #menu-item-474 , #menu-item-475, #menu-item-476, .responsive #top .cart_dropdown, #menu-item-search").css('display', 'none').css('transition', 'cubic-bezier(0.15, 0.47, 0.45, 0.94) 0.9s');
		} else {
			$(".av_header_top:not('av_header_transparency') .logo img").css('display', 'none');
			$(".av_header_top:not('av_header_transparency') .subtext img , #menu-item-474 , #menu-item-475, #menu-item-476, .responsive #top .cart_dropdown, #menu-item-search").css('display', 'block').css('transition', 'ease-in 0.9s');

		}
	});
})(jQuery);
</script>
<?php
}
add_action('wp_footer', 'add_custom_script');

//Disable TMCE html formatting
remove_filter( 'the_content', 'wpautop' );
add_filter('tiny_mce_before_init', 'modify_valid_children', 99);
function modify_valid_children($settings){     
    $settings['valid_children']="+a[div|p|ul|ol|li|h1|span|h2|h3|h4|h5|h5|h6]";
    return $settings;
}

function fix_tiny_mce_before_init( $in ) {

    // You can actually debug this without actually needing Advanced Tinymce Config enabled:
    // print_r( $in );
    // exit();

  $in['valid_children']="+a[div|p|ul|ol|li|h1|span|h2|h3|h4|h5|h5|h6]";
    $in[ 'force_p_newlines' ] = FALSE;
    $in[ 'remove_linebreaks' ] = FALSE;
    $in[ 'force_br_newlines' ] = FALSE;
    $in[ 'remove_trailing_nbsp' ] = FALSE;
    $in[ 'apply_source_formatting' ] = FALSE;
    $in[ 'convert_newlines_to_brs' ] = FALSE;
    $in[ 'verify_html' ] = FALSE;
    $in[ 'remove_redundant_brs' ] = FALSE;
    $in[ 'validate_children' ] = FALSE;
    $in[ 'forced_root_block' ]= FALSE;

    return $in;
}
add_filter( 'tiny_mce_before_init', 'fix_tiny_mce_before_init' );

//Enable shop page editor
add_theme_support( 'avia_custom_shop_page' );

add_action( 'ava_main_header', 'enfold_customization_header_widget_area' );
function enfold_customization_header_widget_area() {
	dynamic_sidebar( 'Extra Header' );
}

Do You guys have any idea what cause this?

Thank You if help me!

Best Regards, Csaba!