Uncaught TypeError Object has no method ‘sortable’

I’ve found a few fixes for this issue already but they aren’t specific to this. I’ve read simple things like Sortable() needs to be lowercase. Of course, I do not have it set as uppercase first.

I already had this working and then suddenly it decided to spit out the following in the console Uncaught TypeError: Object [object Object] has no method 'sortable' on line:210 which correspondes to:

    // Line 210 is below
    $('.sortable').sortable({
         stop: get_post_order
    }).disableSelection();
    // Check new order
    function get_post_order() {
        var post_list = [], pids;
        $('.inner-pop-list li a').each(function() {
            pids = $(this).attr('rel');
            post_list.push(pids);
        });
        $('.export').attr('href', '?format=pdf&pids='+post_list);
    }

It should be updating the post_list array after the list has been reordered. The get_post_order is not running at all. I’ve tried adding the function directly into the stop: function() {...} but still no change.

Any ideas, I’m pretty stumped.

Thanks