I ran into that problem yesterday and somebody told me that you have to spawn a morph target at the frame you want before saving the prop. Then when you open the file you'll see a new dial with the morph and you just turn it until you get the effect you want and then save it. I'm using P4 but I would imagine the same would be true in 5. Feels so good to be able to answer somebody else's questions for a change! :) Good luck!