I updated from 1.0.6 to 1.0.8 and i noticed i can't craft slate bricks anymore, instead it is overriden by the slate roof recipe. Having a quick look at the code looks like the bug was introduced in 1.0.7 with the cabinet variants update. The recipe for roof is made from "slate" oreDict blocks and every variant of slate was added to "slate" oredict in that update. You can now craft a tile from any slate variant too.

I can confirm that bug. You are just able to craft slate roof over and over again. The other recipes seem not to work at all.

Another confirmation. NoMoreRecipeConflict mod lets you workaround, but you cant craft more than 4 at a time.

Fixed in version 1.0.9