How to reproduce the bug:
- Create a INDEXED sprite, transparent layer.
- Change the transparentColor. in Sprite > Properties to Index = 1.
- Select all the canvas with Cmd+A and delete all the black color.
- Draw a path with black color (index = 0).
- Name the layer as PATH.
- Add layer with some drawing (the object to animate).
- Select both layers and run path animation with a 'Rotation: Path Track' option
- Press 'Animate it'
Result: a corrupt image is created for the animation.