Problems saving .py state and trace with Image background, especially when OSPRay is on.
You cannot save a .py file with the OSPRay rendering on (and lighting/background activated. You can sometimes get them to save when no background image is given) I have confirmed this in both 5.6 and 5.7-RC1, and makes setting up scripts for parallel processing very difficult.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information