load.json and tick.json not working

I am trying to setup my first datapack in minecraft 1.21, I've been following this tutorial: https://unicorn-utterances.com/posts/minecraft-data-packs-introduction
Content of load.mcfunction 
say Hello, world!

The tick.mcfunction and tick.json are very similar, and when I invoke the functions in-game using /function they both work. However, they are not running on load or on tick.