I have the same problem with WCSession.default.transferFile it works on already distributed apps also under iOS 14.x but when I compile with current Xcode Version 12.2 (12B45b) it doesn't work. Also the Apple sample code doesn't work. So I can not update apps with the current Xcode Version that is really bad and time consuming.
Will this issue fixed once a time with the next Xcode release ?
When I use a IOS 13.x simulator with watchOS 5.3 it works. But in reality on a current updated device it doesn't work
Totals disappointed !!