I have an app with an intent extension and an intent UI extension. When I call the intent in Siri, the intent UI is displayed, but the response is missing (the <App> says ... part above the UI content). I have tried to create a new intent in the project that should simply show a response without any UI, but the response is again not displayed. Neither does siri play the response via audio.
I already did some debugging and the handle function in the intent handler is definitely called and executes the completion handler with a success response object.
When I call the intent through a siri suggestion instead of calling the shortcut, the intent response is displayed correctly. So the problem seems to restrict itself only to siri.