Planks can only be stacked to 18/20 whenever I have tried, bottom left says 18/20 but I cannot combine another set of 9 freshly cut planks to get a full stack of 20/20.
Wooden logs say they can be stacked to 4 but I can only ever stack 1/4 in my hands. Sometimes I can stack 2/4 after attaching the wooden logs to a wall/fence structure then taking them to hands.