Can't crack open lava rocks

I've had several fall on my sim's lot. She can't crack any of them open. The interaction is avaiable and she'll walk a little way toward them and then do the "I can't get there" wave like there's a routing problem. Opening the lot to edit it, I can't move them unless she makes them decorative (tried that with one and was able to move it, the break open interaction was still there but she still couldn't do it) and there's absolutely nothing surrounding them and no reason she shouldn't be able to reach the rocks to break them open.