When you group your custom recipes you can't click them into the bench to make them. Shift clicking doesn't work too. For example when i click on the spruce log it puts it in the crafting bench. When i click the acacia slabs nothing happens.
Before you ask the recipe works when i put it in myself.
This is kind of odd, I just got my recipes up and running and I could move them onto the crafting table via the recipe book with a single exception I will be posting a bug report for. But maybe it's because mine is in a unique group and not one that shares space with vanilla?