ShareLink does not offer "save to files" when sharing "Transferable" items

In my app I try to use SwiftUI's ShareLink to offer sharing of the app's documents. I followed this video for defining the exported type and the document type. Unfortunately if I use any ShareLink initializer for sharing Transferable items, the option "save to files" is not offered on the displayed share sheet. (Only "copy" is offered, which works if pasted into the destination directory using the Files app, but that is not an acceptable workaround).

PS: com.example.transferabletestis defined as conforming to com.apple.package

import SwiftUI
import UniformTypeIdentifiers

extension UTType{
    static let transferableTest = UTType(exportedAs: "com.example.transferabletest")
}

struct Document:Transferable{
    static let filePackageURL = URL.documentsDirectory.appending(components: "0815.transferabletest")

   public static var transferRepresentation: some TransferRepresentation {
        FileRepresentation(exportedContentType: .transferableTest) { document in
            _ = try? FileManager.default.createDirectory(at: Self.filePackageURL, withIntermediateDirectories: false)
            FileManager.default.createFile(atPath: Self.filePackageURL.appending(components: "data").path(), contents: "Transferable Test\n".data(using: .utf8))
            return SentTransferredFile(Document.filePackageURL)
        }
    }
}

struct ContentView: View {
    var body: some View {
        ShareLink("Share as tranferable item", item: Document(), preview: SharePreview("Test"))
    }
}

Is this a bug? What am I doing wrong?

Sharing the document using the ShareLink for URLs does offer "save to files" but I can't use that in my app for various reasons.