NSTableViewDiffableDataSource + Drag and Drop

I was able to implement drag and drop with NSTableViewDiffableDataSource by subclassing and adding the missing methods. It works but the draggingSession willBeginAt method is never called so I can't provided a custom preview to the dragging. Any tips from AppKit developers or Apple engineers?

class ListCoordinator: NSTableViewDiffableDataSource<String, Int>, NSTableViewDelegate {

    @objc func tableView(_ tableView: NSTableView, pasteboardWriterForRow row: Int) -> NSPasteboardWriting? {
        return NSPasteboardItem(pasteboardPropertyList: row.formatted(), ofType: .string)

    }

    @objc func tableView(_ tableView: NSTableView, validateDrop info: NSDraggingInfo, proposedRow row: Int, proposedDropOperation dropOperation: NSTableView.DropOperation) -> NSDragOperation {
        return .move
    }

    @objc func tableView(_ tableView: NSTableView, acceptDrop info: NSDraggingInfo, row: Int, dropOperation: NSTableView.DropOperation) -> Bool {
        ...
        return true
    }

    

    @objc func tableView(_ tableView: NSTableView, draggingSession session: NSDraggingSession, willBeginAt screenPoint: NSPoint, forRowIndexes rowIndexes: IndexSet) {

        // NEVER CALLED

    }

    

}