I see this when starting a new game as the Thalans in v1.2 Beta 1.

On the first turn, I go into the Ship Builder to design a new colony ship. I choose a cargo hull. In the modules list, Basic Support is listed as Size 5. However, when I add one to my ship, it only uses up 4 units of capacity.

PS - The size shows up as 5 in the tooltip for the installed component.