Assets in wrong places when I reopen my file

Hi, so I am working on a cartoon right now using raster images provided by a client. For the most part, things have gone smoothely, but the last few days, when I reopen the project to keep working on it, half the assets in my scene are in the wrong places, or they shrink and dissapear as they tween. I'm attaching a few sample files. As you can see, body parts are everywhere except where they should be! The scenes were mostly finished and rendered beautifully before this, but when I went back the next day to fix a minor issue, this is what I found. Any advice?