Collapsible section not working | Goldmark config?

support
1

Hi,
I am creating a news section with a blank widget in academic and I want to add a collapsible option to display old news with the

Past News
tags such as shown in this snippet:

(which works here as you can see)
However the collapsible section is not rendered on the website, is this a problem some Goldmark config?

My widget:

+++
widget = "blank"  # See https://sourcethemes.com/academic/docs/page-builder/
headless = true  # This file represents a page section.
active = true  # Activate this widget? true/false
weight = 25  # Order that this section will appear.

title = "News"
subtitle = ""

[design]
  # Choose how many columns the section has. Valid values: 1 or 2.
  columns = "1"

[design.spacing]
  # Customize the section spacing. Order is top, right, bottom, left.
  padding = ["20px", "0", "20px", "0"]


+++
<br/><br/>
+  **09 Mar 2020**: foo
+ **12 Feb 2020**: bar.
+ **01 Feb 2020**: bla.


<details>
  <summary>Click to expand!</summary>

  ## Heading
  1. A numbered
  2. list
     * With some
     * Sub bullets
</details>
2

Double posting identical topics is not allowed.

Please do not do it again.