Multifield data not stored in JSON format

I am trying to switch from Classic UI (ACS Commons Multi Field Panel) To Coral Touch UI and am following the demo linked above but the data is getting saved to the JCR as a String Array for each item under the multi field instead of saving them all under the same property.

You can see below that they are getting stored as flag, link, and title. Instead of being stored as JSON under myUserSubmenu

EDIT: I am running AEM 6.5 and ACS Commons 4.0

This is the Dialog I am using.

<?xml version="1.0" encoding="UTF-8"?>
<jcr:root xmlns:sling="http://sling.apache.org/jcr/sling/1.0" xmlns:cq="http://www.day.com/jcr/cq/1.0" xmlns:jcr="http://www.jcp.org/jcr/1.0" xmlns:nt="http://www.jcp.org/jcr/nt/1.0"
   jcr:primaryType="nt:unstructured"
   jcr:title="User Menu"
   sling:resourceType="cq/gui/components/authoring/dialog">

   <content
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/container">

   <layout
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/layouts/tabs"
   type="nav"/>

   <items jcr:primaryType="nt:unstructured">

   <tabs
   jcr:primaryType="nt:unstructured"
   jcr:title="General"
   sling:resourceType="granite/ui/components/foundation/container">

   <items jcr:primaryType="nt:unstructured">

   <usersubmenu
   jcr:primaryType="nt:unstructured"
   jcr:title="User Submenu"
   sling:resourceType="granite/ui/components/foundation/section">

   <layout
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/layouts/fixedcolumns"/>

   <items jcr:primaryType="nt:unstructured">

   <tab
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/container">

   <items jcr:primaryType="nt:unstructured">

   <usersubmenudetails
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/form/multifield"
   class="full-width"
   fieldDescription="Click 'Add field' to add a new User Submenu title and links"
   fieldLabel="User Submenu Items">

   <field
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/form/fieldset"
   acs-commons-nested=""
   name="./myUserSubmenu">

   <layout
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/layouts/fixedcolumns"
   method="absolute"/>

   <items jcr:primaryType="nt:unstructured">

   <column
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/container">

   <items jcr:primaryType="nt:unstructured">

   <title
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/form/textfield"
   fieldDescription="Enter User Submenu title"
   fieldLabel="User Submenu Title"
   name="./title"/>

   <link
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/form/pathbrowser"
   fieldDescription="Enter User Submenu Link"
   fieldLabel="User Submenu Link"
   name="./link"
   rootPath="/content"/>

   <flag
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/foundation/form/checkbox"
   checked="{Boolean}false"
   fieldDescription="Testing Flag for checkbox"
   name="./flag"
   text="Flag"
   title="Checkbox Tooltip"/>

   </items>

   </column>

   </items>

   </field>

   </usersubmenudetails>

   </items>

   </tab>

   </items>

   </usersubmenu>

   </items>

   </tabs>

   </items>

   </content>

</jcr:root>

I am running into the same issue as you. I am running AEM 6.5 and acs 4.3.2.

@smacdonald2008 or anyone else at Adobe, is it possible to store the values as json on AEM 6.5?