It's even harder when you have the concurrent game that feeds the pet from the box to the vehicle. That's when mystery mountain is unwinnable without boosters. So not fun.
I didn't get all levels of the extra moves a at the end of the game. There are 3 videos to watch for 5 extra moves, but only the first one loads. The other 2 get Xed out. I always need the extra moves or the game won't finish. Is that possibly related to this issue you're describing?