Hi Joseph and Everyone,
I run a little Aperture advisory blog in Hungarian, for my Hungarian readers.
I often get questions that I can answer, and the users are satisfied.
Now I’ve received a difficult question about disappeared images that I followed up with some research and an exchnage of messages with the user, but I can not find the answer.

This is a commercial (wedding photography) use of Aperture, with serious time commitments to deliver images, so it is critical to find a quick solution.

Here come the details:

Issue One:
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Small network with one iMac and one MBP and with one Synology DS211J NAS with 2x2TB disks in a RAID1 array.
All assignments are given an individual .aplibrary that is placed in a separate folder, which also holds the RAW masters.
A couple of weeks ago my reader was working around the MBP, but not touching it. After a period of inactivity he could see from a distance, that the Preview images, one-after-the-other were being replaced by gray triangles with exclamation marks. As if a wraith had been invisibly fiddling with his files.
Some of the images were changing, being replaced by tiny, rectangular, cropped images from another library (!!!).
He quickly quit Ap, then restarted with Option-Cmd and went through all the repairs and the rebuild. After the maintenance and rebuild the situation remained the same. He gave up work with the MBP.

Issue Two:
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We are now on the iMac, in the Library of an assignment with 2000 masters and 200 adjusted/finished images, a part of them, luckily, already exported.
Again, apparently without any human action, the images, seen in Browser view, one after the ather, spectacularly changed:
- Some turned by 90 degrees and got distorted - these later were possible to recover by Generate Thumbnails.
- Most of them changed to a camera-icon (though these are photos), and in the bottom-right corner „The referenced image’s master is offline” badge appeared.
In the “Locate Referenced Masters”-dialog all images are shown as existing in their correct location.

When clicking at such a thumbnail, the preview of the adjusted version appears with the “Loading…” message then, after it has been loaded, a translucent gray layer comes over it and the bricks in the Adjustments inspector get grayed out.

In some cases the preview finishes loading nicely, but the master is still shown as offline. When my reader attempted to export full sized JPG versions - you won’ believe: the result of the export was a copy of the RAW master!

After confirming that all standard repair processes have been completed (permissions, repair- and rebuild database, relocate referenced masters, etc) I suspected that the RAID might cause the problem, as it is using 2 disks and I know that Aperture links each image to the UUID of the disk which holds the image. I thought while the logical path is unchanged, the physical location - and hence the UUID - might change. But we tested this, moving a Library to a new external HD and then locating and reconnecting masters. In the result the images showing a camera-icon still could not be found.

I’m getting rather desperate with this case, and would appreciate any advice that might bring us closer 1) to find the cause of the issues 2) to solve it.
Many thanks.