Categories in Menu not Showing Up

Happy snowy Tuesday (at least where I am!),

There were some default categories set up when I first started creating this website that came with the theme, which is Kadence. I deleted them, and added the categories the client wanted for his online art gallery. When I went to Appearance>Menu to add the categories as a drop-down from the menu, only the default categories I deleted are showing up. I double-checked the categories again just to make sure they were gone, and they were. What am I missing? His website is currently in a staging environment now via WP staging just FYI. Thanks for your help!

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