I'm a first time Buefy user.
When I tried to use the b-icon component,
I was confused when I saw that the icon doesn't show,
instead it just showed an empty block element, as if the icon was there.
I tried using a different icon pack but that also didn't work.
What the official Buefy documentation doesn't tell you is that you have to install the Material Design package, then import it in your main.js file.
npm i @mdi/font
import '@mdi/font/css/materialdesignicons.css'
I'm guessing that for a different icon pack you just need to do the same with the relevant package.