Header Overlay on Image Buttons don't appear

[kfpro]

The header overlay buttons don't appear. Added everything as instructed in the docs but seems to be a bug.
I'm using Github Pages and I am new to Jekyll.

from the markdown file:

title: "About"
permalink: /about/
date: 2018-01-28
tags: [data wrangling, data science, messy data]
excerpt: "Image : Gallery"
header:
overlay_image: /images/ecopark_small.jpg
overlay_filter: 0 # same as adding an opacity of 0.5 to a black background
caption: "Photo credit: Gallery"
actions:
- label: "Foo Button"
url: "https://kfpro.github.io//about/"
- label: "Bar Button"
url: "https://kfpro.github.io//about/"

layout: archive
author_profile: true
last_modified_at: 2019-08-27T15:46:43-04:00
toc: true
mathjax: "true"

From the generated website:

My page about

A screenshot:

Bug Screenshot

Environment

• Minimal Mistakes version:
• Ruby gem or remote theme version:
• Jekyll version:
• Git repository URL:
• GitHub Pages hosted (if yes provide URL to site):
• Operating system:

Expected behavior

Steps to reproduce the behavior

Other

[mmistakes]

Not a bug.
You're using a really old version of the theme... 4.9.0. This version doesn't have support for adding the button links in the header.

Upgrade to the lastest version 4.20.2.

[kfpro]

Sure , Thanks for the prompt reply, really appreciate it !