Conditional logic 1.6.1 - JavaScript Error

Hello, first I'd like to start by saying I am super excited about these speed improvements.

However, upon updating, I now get the following JS error in the console (as an aside, the version number of the js file still reflects version 1.5 in the PHP).
Uncaught TypeError: $field.closest is not a function
at getFieldScope (conditional-logic.js?ver=1.5:265)
at conditional-logic.js?ver=1.5:211
at Array.forEach (<anonymous>)
at isLogicCorrect (conditional-logic.js?ver=1.5:200)
at Object.<anonymous> (conditional-logic.js?ver=1.5:308)
at Function.each (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,moxiejs,plupload&ver=4.9.8:2)
at Object.<anonymous> (conditional-logic.js?ver=1.5:301)
at Function.each (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,moxiejs,plupload&ver=4.9.8:2)
at runConditionalLogic (conditional-logic.js?ver=1.5:300)
at init (conditional-logic.js?ver=1.5:513)
<code></code>

Which is referring to this block of code:

function getFieldScope( $field ) {
// If the current field is in a group clone, then all the logics must be within this group.
var $groupClone = $field.closest( '.rwmb-group-clone' );
if ( $groupClone.length ) {
return $groupClone;
}
// Global scope.
return '';
}
<code></code>

I haven't had a chance to dig deeper into that yet, but it is breaking the clonability of my metaboxes in almost every location where they are used.

Thanks!