Adding inventory back, "buy" button doesnt appear

Im running an older 1.7 install.

a producted was configured to track inventory, but then the quantity was set to 0, and it configged to disable buy button on low quantity.

now I try to tell it to not track inventory, button still doesnt appear. I tell it again to track, but do nothing when Quantity is low.. still no buy button.

Is this a bug or am I doing something wrong?

1. Ensure that 'Disable buy button' is checked (admni area - product variant details page)
2. If you mean category or manufacturer details page (not product details page), then ensure that you have only one published product variant.