I was having the same issue, I just force quit Xcode and the Simulator, and now it's working for me.

Not sure if you figured it out yet, but EventKit is only available through UIKit (old way of working with views). It's not implemented through SwiftUI yet. But, you can use UIKit's UIViewRepresentable to convert UIKit views to SwiftUI views. Which would help in making EventKit work in SwiftUI views. Here's a YouTube video I found that explains how to do this, if that helps https://www.youtube.com/watch?v=1GYKyQHVDWw