The advancement that unlocks the soul campfire recipe can be achieved by obtaining either soul sand, or a stick.

Since sticks are one of the very first items a player obtains, this is one of the very first recipes to be unlocked. It's a bit unusual, since soul campfires are an otherwordly-looking item that aren't truly obtainable until entering the nether.

The other two soul items are only unlocked when obtaining a nether ingredient: torches when obtaining soul sand/soil, and soul lanterns when obtaining soul torches. So when you gather soul sand for the first time, the game will inform you that you can now craft soul torches, but won't inform you that you can now craft soul campfires, since you already unlocked that recipe ages ago.

I think the intention was to unlock this recipe after both sticks and soul sand have been obtained, and likewise for stick and coal for the regular campfire.