Wooden pressure plates and buttons aren't grouped in the recipe book.

The bug

Wooden pressure plates and buttons aren't grouped in the recipe book, even though planks, bark, doors, trapdoors, stairs, slabs, fences and fence gates are.

See attached screenshot. (2×2 Crafting grid) (The birch planks and birch bark actually cycle through all available wood colors, but I was too lazy to create a gif.)