Currently the mod includes recipes to convert between the planks and timbers for the various woods. The problem is that it currently is set up as 4 timber -> 1 plank and 1 plank -> 8 timber, so crafting timber from a plank gives enough to recraft 2 planks.

But this is not the case. At me all works as it is necessary.
Are you sure that another mod does not affect this?

Blegh I have no idea, a fresh instance with just MW and JEI indeed doesn't have the problem, but I have not the slightest idea what mod could be affecting it. I'm tweaking the recipes myself anyway, so whatever.