Top Navigation Suddenly missing from site

Our site uses city gov theme. I logged on yesterday and the top navigation is missing. it is enabled and nothing has changed. I have temporarily added a manual wordpress menu block to the homepage and a few other pages. I have tried deactivating plugins. I added a photo of the missing nav as well as what it used to look like. Can you please help me get the original navigation back?

The page I need help with: [log in to see the link]