This issue is repetible.
It could happen in case if SpinningWheelAnimator.addRotationAnimation() starts before the WheelView.addWheelLayer() has been finished. In this case layerToAnimate property of animationObject is nil, so the action animationObject?.layerToAnimate?.add(transformAnim, forKey:"starRotationAnim") did nothing and there will be no animation.
I've solved the problem by manualy making a time gap between initialization of SwiftFortuneWheel() and starting animation. A timer with interval 0.1 sec has helped me.
This issue is repetible. It could happen in case if SpinningWheelAnimator.addRotationAnimation() starts before the WheelView.addWheelLayer() has been finished. In this case layerToAnimate property of animationObject is nil, so the action animationObject?.layerToAnimate?.add(transformAnim, forKey:"starRotationAnim") did nothing and there will be no animation.