I've been using Drupal Commerce for about 1 year now as an on-line box office for a theatre company (www.farmersalleytheatre.com). Everything has been going great except for we recently ran into an issue when there is only 1 product type left, the Add to Cart Form doesn't display the product list anymore. In my setup, each product is a ticket to a particular show. As the shows either sell-out or their date has passed, the site admin goes in and disables the respective tickets. This eventually gets us to a situation where there is only 1 product left and then the product drop-down completely disappears from the page. I have not been able to figure out a way to keep it displaying even if there is only one product.

You can see my particular setup on the box office page (http://farmersalleytheatre.com/box-office). Right now the work-around is to keep an older show active, but that obviously is not an ideal solution. Any help would be greatly appreciated.