Does the recipe shown in the mod page not work for you?

adding new dyes works, but not crafting the first palette (sorry for taking long to answer i have been ill)

I tested this again and it works:

If you mean you can't craft a palette with no colors, yes you can't because that would be the slab's crafting recipe. And there is no reason to craft an empty palette anyways.

I thought of using clay instead of planks but it is too late at this point.

no i mean i cant craft palettes, if i cheat one in i can add colours to it, but i cant craft a basic one