FMovieSceneTrackCompilerArgs::DefaultCompletionMode is undefined value in UMovieSceneTrack::Compile if using add new camera and cameracut button of sequencer.
When creating another track, processing runs in the following order.
FMovieSceneTrackCompilerArgs::DefaultCompletionMode is not undefined value.
But when creating camera and cameracut track using the button, processing runs in the following order..
So, FMovieSceneTrackCompilerArgs::DefaultCompletionMode is undefined value.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-58335 in the post.