Manually adding a new post kind to the Post Kinds Plugin for WordPress by Chris AldrichChris Aldrich (BoffoSocko)

Chances are that the icons are fine, you just need to do a version bump on the plugin to get the internal cache to flush to show them.

I just don't understand what the following means.

You’ll want to have one icon named kindname.svg in the svgs folder and another named kinds.svg in the plugin’s root folder. The kinds.svg is a special ‘master’ svg of all of the kinds icons bundled together. If it helps in matching the icon set, all of the current kind icons are made with Font Awesome icons which have the appropriate licensing for distribution.

I downloaded and place a Font Awesome icon called 'beer.svg' into the svgs folder. However, the kinds.svg file already existed in the plugin's root folder. The kinds.svg file does not apparently have all of the kinds icons bundled together since beer.svg is not in that file (it's a binary file). I really don't understand how this worked for you but not me. There must be a step I am missing.