I wasted half a day on the same issue. My solution is below. 1.Make ipa file by Xcode. But you choose Product - Achive - Distribute App(Not Select Validation App), and choose App Store Connect - Export. 2.Upload ipa file by "Transporter" You are able to Validation and Delivery. Big Sur ver11.1 Xcode 12.4 Transporter Ver1.2.1

I read Apple's documentation and decided from the explanation of RunLoop, run (), but that is probably a mistake. I'm calling it in the Main thread. Technically, I should have used semaphore and DispatchQueue, but I was able to achieve the desired behavior with RunLoop, so I decided to use it. I was very disappointed・・・・ Thanks

I got the information from Apple by DTS. The comments are below. This is a known issue. However, nested run loops are not a recommended practice today due to complexities of timing event loops and the response chain. Could you replace the logic which requires spinning the run loop with a call to performSelector or a timer instead? So I rewrote the code using "An escaping closure to handle the completion callback with Timer". It works good, but there was a lot of code changes and the nesting was very deep(In the sense of the caller). I had no other ideas. ex) func delayedDisplay(completion: @escaping () -> Void) {    let partString = moji.prefix(1)    if (moji == "") {      print("<END>")      // 5. Invokes the completion handler when the recursive work ends.     completion()      return   }        print(partString, terminator: "")        // 2. Schedules a single use timer to perform recursion.   _ = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: false) { timer in      // 3. Perform some work.      if let range = self.moji.range(of: partString) {        self.moji.replaceSubrange(range, with: "")        // 4. Passes the completion handler again for proper recursion.        self.delayedDisplay(completion: completion)     }   } }