There’s actually a simple fix to this. As @JacksonBates says, Google depreciated navigator.geolocation on Chrome so that it only works with https sites, not http ones.
If you put add https:// before 'codepen.io/ in your browser it works; then if you put links to your codepen with the same https:// prefix, when people access the page, it works.
The other solution is to use http://ip-api.com/json/?callback=, but it isn’t as accurate.
I actually had a pop-up message when I looked at a Codepen page asking me to add the https://, and I think I may add my own pop-up to that effect as well.