Can't seem to create product combinations. I select the product, change to Product with Combinations, select the attribute I want to add, click Generate, Product Updated message appears, but nothing changes - no combinations/attributes are created. Using PS 1.7.4.3 with Alysum theme. I have products with combinations that were imported when I upgraded from PS 1.6 to PS 1.7, but I can't create any new ones. I have tried disabling Friendly URLs - no difference.