Faces gone after upgrades to Mavericks and iPhoto database.

Question

After upgrading to Mavericks from Mountain Lion, the iPhoto Database had to be upgraded by iPhoto to work with Mavericks. It went thru the process and afterwards many (but not all) of my Faces were gone. The photos are still there...and they're still tagged with the appropriate Faces name, but they will not show up in Faces. The only way I can get them to show up there is to delete the Faces names that are already on the photo and re-enter the Faces from scratch. But since there are at least 1500 photos that are affected, there's got to be a better way! I've done each of the following to no avail:
1) Repaired permissions.
2) Rebuilt Thumbnails.
3) Repaired the Database
4) Rebuilt the Database
5) Restored the Database from Time Machine to pre-Mavericks. The database had to be converted by iPhoto like before. And the results are the same - lots and lots of Faces missing - though everything else appears to be there. The only thing I can see is that it's the same set of years where the Faces are missing (it's something like all Faces from 1942-1970 are missing - but the ones before and after that are there).
Anyone have any ideas? Thanks in advance.

Answer 1

Since you've tried all of the standard fixes there's only one left: 
1 - delete the iPhoto preference file, com.apple.iPhoto.plist, that resides in your
     User/Home/Library/ Preferences folder.
2 - delete iPhoto's cache file, Cache.db, that is located in your
User/Home/Library/Caches/com.apple.iPhoto folder (Snow Leopard and Earlier).
or with Lion, Mt. Lion or Mavericks delete the contents the User/Library/Containers/com.apple.iPhoto/
Data/Library/Caches/com.apple.iPhoto folder.
3 - reboot, launch iPhoto and try again.
NOTE: In Lion and Mountain Lion the Home/Library folder is now invisible. To make it permanently visible enter the following in the Terminal application window: chflags nohidden ~/Library and press the Return key - 10.7: Un-hide the User Library folder.
If you're running Mavericks, 10.9,  go to your Home folder and use the View ➙ Show View Options menu to bring the this window:
where you can check the Show Library Folder checkbox.
If no change try rebuilding the thumbnails again.
OT