Picture-in-picture in iOS fails with saying that the activationState is something other than foregroundActive but it is actually foregroundActive

I am implemeting Picture-in-picture on iOS. I added the background mode capability. When I call isPictureInPicturePossible, it returns false with error:

pictureInPictureController failedToStartPictureInPictureWithError Error Domain=AVKitErrorDomain Code=-1001 "Failed to start picture in picture." UserInfo={NSLocalizedDescription=Failed to start picture in picture., NSLocalizedFailureReason=The UIScene for the content source has an activation state other than UISceneActivationStateForegroundActive, which is not allowed.}

But I when I log the activationState, I can see that it is actually foregroundActive. Any idea what could be the reason?

(before that isPictureInPictureActive returns true, isPictureInPictureSuspended returns false, isPictureInPictureActive returns false.)