Q: Aperture missing masters after importing iPhoto library

I have a large iPhoto library (about 14,000 photos), which appears to work properly when opened directly in iPhoto 9.6.1 or directly in Aperture 3.6. When opened in either of those, all of the "Originals" or "Masters" can be properly located, and there are no problems.

I would like to merge this library into an equally large Aperture library. I tried doing this by using File -> Import -> Library, which ran with no error messages. After the import job, most of the photos imported from iPhoto show an error icon, indicating they are missing their Master. There are about 9,500 photos with missing masters, according to Aperture. I can use the "Locate Referenced Files" tool, and in there I see all of these photos with missing masters have "null" as the volume name in their path, and their path starts with the year of the import job. Example path:

2012/01/03/20120103-185643/DSC02345.JPG

To reconnect the master, I can navigate to the iPhoto Library container, and click on the "Masters" folder inside the library container. As soon as I click the "Masters" folder, the Referenced Files tool locates the folder (since the rest of the path matches). See the screenshot:

This method won't work for me, though, because the "Reconnect All" button does nothing. This will only reconnect one photo at a time, then the focus of the top part of the Referenced Files tool changes, and I need to re-click the missing missing file, re-click the "Masters" folder, and click Reconnect again. I can't do that 9,500 times.

So why is Aperture losing these Masters when it imports from iPhoto? Is there a way to reconnect all of these at once?