One save per session. That's not one creature, that's one use of the "Save" button. I honestly have not had a single creature disappear since I started doing that. I had such a hard time with the disappearing problem originally, so, form my experience, reverting to a single save per session definitely seems to make things better.
Currently, my "My Creations" is at 109. They are all displayed. If I hit the save button once, I immediately exit and re-enter.
The program will try and trick you. Sometimes you'll save, then go to exit. Randomly, even though you just saved and haven't made any changes, the game will ask you upon exiting, "Do you want to save so and so creature?" You've already saved, so press no. I think when people say they tried the one save thing and it didn't prevent the problem, this is what's getting them. It's so natural to hit, "Yes," but doing that is bumping the number of saves per session from one to two.
One use of the save feature can be kind of annoying, I'll admit. Last night, I had around 17 creatures that I had yet to give descriptions to and upload. After giving one creature a description, I would save, then reboot the CC. Not exactly ideal, but I think it's more annoying to deal with your creations disappearing.
EDIT:
Will said they are going to keep it in the game because of the things people are making.
What? No, not the disappearing creatures bug. God no. o_o He was talking about bugs like invisible limbs, and invisible torsos. Things of that nature. Not a bug like the disappearing creatures bug that does nothing but make the experience decline for everyone involved. o_o
