I already contacted jaquadro with the following just wanted you in the loop in case it is a compatibility issue.

Actually, it says 1 stack, but you cannot place items into them. I used a diamond builder's wand from Better Builder's Wand mod to place several 1x1 and 2x2 onto existing drawers. They placed, but this is what they showed:

My son had me try [shift] + [right click] to see if it updated the capacity, but that was a no go. I could see the gui, but when I left it it was still 1 stack.
So far breaking and placing by hand restores the drawer.