Hello
We’ve just released the new version of Meta Box Group which supports for multi-level nested groups. Please try it and let me know the result.
PS: Due to JavaScript problem, the media field and WYSIWYG field couldn’t be cloned in multi-level nested groups. So please don’t use them.
You can automatically update the plugin using the Meta Box Updater or manually download the extension, unzip and upload to your site, overwrite old files.