Hmmm yeah it doesn't quite work 100% right does it... I started having a few weird problems with my example as well, like objects not moving after they came to a complete rest, even though the player had higher mass etc than the object being pushed.
Either one of a few things will need to happen:
1. Make your own custom movement engine for your character, and ditch the platform movement.
2. Don't use physics objects at all
3. Try making your player just ue platform movement, and make an invisible "detector" object thats always right next to your character which has physics properties. Maybe using a sperete object would work better?
4. Team Scirra will need to address the issue of multiple behaviours on a single object
5. Make it so non physics objects can interact with physics objects, as you suggested it may have been there before.