Problem with shape tween

I have been trying to get a shape tween with two vector shapes to work. On the frame for the shape I’m tweening to, I get the warning exclaimation point saying that Shape tweening will not occur on layers containing symbols or grouped objects. It still sort of works - however the shapes on the frames between the two key frames are outlined rather than solid.

An example of the problem I’m having can be viewed here:

I’ve also uploaded the source FLA here:

I’ve done “Break apart” on all of the objects, so as far as I can tell there are no symbols or grouped objects.

If anyone has any ideas, I’d appreciate the help!