It works fine in one language, but in the other just the tabs are showing, not the inside of them, here's some of the code
This problem also happens in all the other registered meta boxes
The WPML languages are English (primary) and Italian
private function register_post_meta_boxes(&$meta_boxes, $prefix)
{
$fields = [];
// Slideshow
$fields[] = [
'id' => $prefix . 'slideshow_media',
'type' => 'image_advanced',
'name' => __('Slideshow Media', 'snip'),
'tab' => 'slideshow'
];
// Interview
$fields[] = [
'id' => $prefix . 'is_interview',
'name' => __('Is this post an interview?', 'snip'),
'type' => 'checkbox',
'tab' => 'interview'
];
$fields[] = [
'id' => $prefix . 'interviewed',
'type' => 'user',
'name' => __('Interviewed', 'snip'),
'hidden' => ['is_interview', '=', '0'],
'tab' => 'interview'
];
$meta_boxes[] = [
'title' => __('Additional Metadata', 'snip'),
'post_types' => 'post',
'tabs' => [
'slideshow' => [
'label' => __('Slideshow', 'snip'),
'icon' => 'dashicons-format-gallery'
],
'interview' => [
'label' => __('Interview', 'snip'),
'icon' => 'dashicons-admin-users'
]
],
'fields' => $fields
];
}