And now installed version 0.9.9.2 and in this version everything is working. It works on the production site too. So i really think you have to squash some bugs 😉

Ok, I have repoducable steps to show that reordering is really not working:

1: install WordPress https://wordpress.org/download/ (default English version, install with English language)
2: install Piklist 0.9.9.9 https://wordpress.org/plugins/piklist/
3: only activate Piklist plugin, and the plugin below
4: Add my plugin below:

/myplugin/myplugin.php:

<?php
/*
Plugin Name: My plugin
Plugin Type: Piklist
Version: 1.0
*/

/myplugin/parts/meta-boxes/mymeta.php:

<?php
/*
Title: Testupload
Description: Testupload
Post Type: page
*/

piklist('field', array(
    'type' => 'file',
    'field' => 'sliderimg',
    'label' => 'Slider img',
    'description' => 'Upload',
));

As you will see, you cannot reorder. I think we have now the exact same setup (English version, brand new database, only Piklist installed)

Can you please test it on your system too? I am sure it will not work on your system too.
Or maybe I have wrong options in my meta file?

Hi, I removed the sortable and validate parameters and added:

function my_custom_init() {
  remove_post_type_support( 'post', 'custom-fields' );
}
add_action( 'init', 'my_custom_init' );

But no change. I have the most simplest Piklist configuration with only the code I gave you. And it is not working. I am trying furter.

Thanks so far!

Thanks for your reply @Jason, taxonomies are indeed the way to go, thanks for pointing at them!

Thanks @Jason,

At the moment I got it working again. Strange, but in my case it did help to remove the old posts in database and the transients.