Using ver 3.80 with Bender theme...
Our hosted server suffered a major failure, and I had to reload Osclass. Prior to this failure, when a person wanted to create a new listing, there were separate fields for 'Category' and 'Subcategory'. The user first selected the desired Category, and next another dropdown would display the subcategories.
Now, only a 'Category' field is available, and the dropdown menu contains all categories/subcategories in one very long list. I have the option in Settings >> General "Allow users to select a parent category etc) NOT checked, like I had before the failure, but it still does not cause two separate Category/subcategory fields to appear.