Sorting by Winery works for wines that you Searched for and added to your Cellar. For those wines, we store and validate the Winery as a hidden field.
However, sorting by Winery will not work for custom wines that you created, because we do not necessarily know the Winery. This is an easy change for us to add a Winery attribute, and I have added it to our product roadmap.
Thank you for your input!