Nested Tabs in Accordion – Content not displaying

I installed this plugin and have gotten accordions to work correctly, pulling content from posts within a certain category. Now I need to have tabs within these accordions to display various content, and while I can get the tabs to show up, the content within them doesn’t show. I tried simplifying it and building the whole thing in a page without drawing content from posts, thinking maybe that’s where the issue was; still no joy. Here’s the code that displays perfectly with the exception of content;

[wptabs type="accordion" ]
[wptabtitle]Handling[/wptabtitle]
[wptabcontent]
<div class="wp-tabs">
<h3 class="wp-tab-title">Inner 1</h3>
<div class="wp-tab-content">Contents of inner tab 1.</div>
<h3 class="wp-tab-title">Inner 2</h3>
<div class="wp-tab-content">Contents of inner tab 2.</div>
</div>
[/wptabcontent]
[wptabtitle]Handling[/wptabtitle]
[wptabcontent]
<div class="wp-tabs">
<h3 class="wp-tab-title">Inner 1</h3>
<div class="wp-tab-content">Contents of inner tab 1.</div>
<h3 class="wp-tab-title">Inner 2</h3>
<div class="wp-tab-content">Contents of inner tab 2.</div>
</div>
[/wptabcontent]
[/wptabs]

Any thoughts?

https://www.ads-software.com/extend/plugins/wp-ui/