I am using Aperture 3.5.1 and running Mavericks OS. This is more of an irritant but has anyone else had this problem. Whenever I import from a memory card into a new Project and then drag the new Project into an existing Folder and then I click on the new Project, none of the new pictures appear. It looks like an empty Project. I have to either switch to a different library and then switch back or quit Aperture and reopen it. Then all the pictures appear. I have not lost any pictures yet, but I am worried about the stability of my pictures.
This has happened to me many times. Sometimes the images would reappear after a while; sometimes they would appear only after Aperture is relaunched. Now I create new projects and move images (Select All in source projects), instead of moving the projects. I just acquired a new iMac. Maybe I’ll try moving a project some time - if and when I feel really adventurous.