I think that it is not working with the List Field. As in your function you are using $value = maybe_unserialize($value); and the value is not an array or a serialized string. It's indeed stored like 23|23|23|232.
I will try to change the code to create an array out of this and see if the list field is displayed properly. If it does I will let you know, so you can update the core of your plugin.