Looks like you can either ensure that there is a "dummy" item to start with and them remove it immediately after applying bindings or a potential workaround would be to get access to the widget and set floating
to true.
Something like: sortable: {data: Seats, connectClass: false, options: { activate: setFloating } }
with:
setFloating: function() {
$(this).data("uiSortable").floating = true;
}
Both seem like a workaround, but seem to make it work properly.