I have seen the same results and posted a query last week.
Several other people have mentioned the same thing, although for most people it works fine. I have to believe it's a bug at this point, although I do not know why it happens to some people and not others. That would imply there is a pattern we can find that reveals the bug, and a different pattern in which everything works fine.
So, questions back to you:
- Do you have "Generate preview immediately" set?
- Have you ignored Aperture and iTunes for a while and then come back to see what happens?
- Do you have any projects which are synced correctly?
- For your two projects that are not synced correctly, what is your project and album structure to get to those? I.e., "Folder/Folder/Project/Album", or something like that... I'm wondering if the problem is with some sort of nesting of containers... When I get home I can post the structure of my problematic photos.
Generate review automatically is set, but it only does so when loading. I have scanned in old negatives and am retouching them to remove scratches and dust. I was trying to get the previews updated so that they can sync to my iPad.
All but the two projects where I forced the previews to regenerate are fine.
I have my photos separated into events by year. Since I have a Mac, I don't have to worry about having iTunes look in nested folders. It gets all the photos from Aperture.
It looks like Leonie's thread pointed to the solution. I switched from one Aperture library to another, quit Aperture and moved back to the original when I restarted it. iTunes sees the previwes correctly.