Zen Cart version: v1.3.9f

I have a problem where I'm using the SBA module and this one together and the out of stock isn't working properly when one of the attributes is out of stock.

I have products that come in various sizes. If I add stock to one of the sizes, ALL size options become available in the grid. Even if I specifically set the quantities of the other options to zero, they still show up on the product page.

Surely this isn't how it is supposed to work.

Any ideas?