Callkit UI does not pop up

Hi, I am using Callkit to make a VOIP application recently.

But when I use Callkit to make a call out, after the call is connected, I hang up normally, and another call comes in and the following interface appears;







When I click on the titlebar, the interface will pop up



This problem can also be reproduced in the SpeakerBox sample code;


Model Name: iPhone 7
Software Version: 14.1