404 ERROR for one of my categories

This page is supposed to show all of my blog posts under that category but every time I click on it, it shows up as 404. I tried to create a brand new category multiple times but each new category I make is showing up as a 404. All of my other categories are fine.

I called WordPress support and they said it was an issue that will happen with any new category going forward and wanted to charge me $150 to have someone fix it. I’m hoping someone here can help me figure it out, but I feel like it is probably a simple troubleshooting issue and doesn’t need to be $150 to fix.

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