Cannot highlight category in menu when on single post page

I can’t seem to get current-post-ancestor to work as outlined in this tutorial: https://designisphilosophy.com/tutorials/highlight-current-page-or-category/

My site is not currently live so I can’t provide a link, but here is the CSS my menu uses: https://pastebin.com/wX4GHujK and here is the PHP: https://pastebin.com/teVm1aRv

When I add the post ancestor wrapper to my CSS it is ignored by the website. However, I looked at the page source and the menu does use the “current-post-ancestor” wrapper.

I looked at the theme forums (“Origin”) but that resulted in nothing.

Any advice?