OK... I'm going cross-eyed on this one. A long-overdue product feed update has resulted in a new category tree at my site.
The site uses Premium Responsive Design Felicity. You can check it out a www.firesidecamping.com.
The link bar on the left has updated. If you click on "Lights" you'll see and can click into the subcategories of Flashlights, Headlamps, and Keychain Lights. What doesn't work is the top category of LIGHTS. It doesn't display the subcategories shown on the left navigation bar.
I realized that on the left-hand navigation, but on the categories.asp page, I was having the same issue.
When I went in and started flagging "recommended" products, I realized I had two categories named "Lights"... one for categories and one for products. Made a change and solved the issue.