Good day!
I met this after 1.8 update.
If I try to edit any of previously saved model (made by me or other users), for example, after adding a wing, it savws normal. But when I try to use that model in game, any changes of existed parts are shown, but any parts added by me are invisible but still listed on ship. Also sometime size of the ship parts, which was ajusted by me, randomly jumps on edited model.