Apps cannot be found

I moved my iTunes library to a network drive. This works fine for music, but causes problems with syncing apps to the phone. If I buy a new app on the phone, it will sync over correctly. If I buy the app via iTunes on the Mac, when I attempt to sync the phone, I get an error message that the app could not be found, and the app will not get synced to the phone.

If I select "get info" on the app in iTunes, it shows the correct path on the network drive. So clearly it knows where it is. I don't understand why I'm getting this error.