Sorting of items in a hierarchical table does not work!

Model

struct File: Decodable {
    /*File name (including relative path)*/
    let name: String
    /*File size (bytes)*/
    let size: Int64    
    var children: [File]?
}

extension File: Identifiable {
    var id: String { name } // unic for node
}

Table

struct TableView: View {
    
    @Environment(AppContext.self) private var appContext
    @State private var fileTree: [File] = []
    @State private var sortOrder = [KeyPathComparator(File.name)]
    @State private var selectedFile: Set<String> = Set()
    
    var body: some View {
        Table(fileTree, children: .children, selection: $selectedFile, sortOrder: $sortOrder) {
            TableColumn("Name", value: .name) { file in
                ItemName(for: file)
                    .padding(.leading, 5)
            }
            .width(ideal: 300)
            TableColumn("Size", value: .size) {
                Text($0.size, format: .byteCount(style: .memory, spellsOutZero: false))
                    .frame(maxWidth: .infinity, alignment: .trailing)
            }
            .width(ideal: 50)
        }
        .onChange(of: sortOrder) { _, newValue in
            fileTree.sort(using: newValue)
        }
    }
}

However, sorting only works for the root elements. Is there something I’m missing?
Thank you.