Hi Blay,
I think I’ve isolated what the issue is and I’m afraid that I don’t have a good workaround without a source modification. It is a race condition between texture and sprite loading during cooking, as the ConditionalPostLoad call doesn’t block for the texture when running the cooker as a separate commandlet like it does when run from the editor. This means that the bug shouldn’t show up when you use Launch On, which defaults to cook-in-editor, but will show up when packaged via Package or UFE.
I’ve filed a ticket UE-14171 and I’ll get that fixed for 4.8. The full fix will be to get size via a different mechanism, but as a quick hack you can try skipping the resizing code by changing UPaperSprite::NeedRescaleSpriteData() to always return false.
Cheers,
Michael Noland