Not working in Chrome

I’m using the Studiopress Agency theme (not the pro version, the previous version) on this website: http://portsmouthhistory.org. In the Chrome browsers on both PC and Mac, the plugin is not working.

The icons show up in Firefox and Safari. Take a look at the footer of the page in these browsers and the icons are there. But not in Chrome.

How do I fix this?

https://ww.wp.xz.cn/plugins/simple-social-icons/