Swift animation completion bug with release build settings

There are two view controllers, Initial and modal. We have animation in the initial controller and also animation in the modal controller. Each animation have completion block. We set build scheme Run –> Build configuration to Release. Run app, go to modal controller and run the animation. After animation (in the modal controller) the completion block of animation in the Initial controller is invoked instead of the completion block in Modal controller. Is anybody also experiencing with that? Any suggestions?

Sample project here