The afternoon that we were leaving for holiday I discovered that I couldn’t use iTunes to sync a movie (or a video Podcast) to my daughter’s iPhone 4S.  Sync was normal for all other devices but on her iPhone we got stuck at the agonizing “Waiting for changes to be applied” prompt . If I waited 15 minutes or so the sync “completed” without an error message, but no movies were transferred. When I inspected the iPhone contents from iTunes I saw ghostly outlines of the movies I was trying to transfer.
- sync of non-DRMd home video (didn’t work)
- turn off all sync for movies then sync then remove media then try one movie
- Parental Controls toggle including age range check
- restarts of iOS and OS X
- PhoneView inspection of the file system (iOS CloudAssets directory was empty post iOS 7.1 fix for the Other Data cache bug.)
- Sign out and sign in to App Store from iOS and OS X iTunes.
- Looked for anything in Console.app related to iTunes (nothing)
- Backing up, wiping (“restore” to default) iPhone, then restoring it
Could try initiating a sync with a different computer and letting it overwrite the link with this one. Then, back again. That would clear any caches...
That worked. The key here is that when you sync an iOS device to a different iTunes instance you lose all of your media, but you don’t lose anything else. You don’t lose Apps or App data or iCloud data, etc . If you’re old enough to remember the iPod you can see that when the iTunes is treating the iPhone as though it were an iPod. I did this:
- Backup iPhone on Primary iTunes. (iTunesP)
- Switched to the admin account on my Mac and launched iTunes there (iTunesA).
- Selected a single short movie to sync (and nothing else). iTunes warned me all media (but only media) would be wiped from my iPhone. (Note difference from the usual “restore” and “restore from backup” behavior.)
- The movie synched normally.
- Switched back to iTunesP. Did same thing, again iTunes warned me all media would be removed. The moved synched normally.
- Turned on sync for Music, TV, Photo, etc. iTunes remembered all of the prior settings so this went quickly.
- We downloaded the (great) movie Frozen from iCloud to our Apple TV very early in its release cycle. There was odd behavior when I later downloaded a copy to iTunes; the new download had a slightly different file size and iTunes seemed to think they were different movies. I can’t remember how I fixed that … (probably deleted and redownloaded)
- Since wiping the phone and restoring from backup didn’t fix the problem, it’s likely related to something that’s backed up.
- Even after I synchronized the iPhone with my admin account iTunes instance, I still saw the ghostly outlines of the movies I’d been unable to sync previously.
- fn -
 This was a week ago, and I can’t recall if TV shows were behaving normally. I think they were, which is extra weird so maybe I’m remembering incorrectly.
 Pre-iCloud days I used to sync Calendar/Contacts for my wife on one iTunes account, and media on a different iTunes account. In the iPod era Apple was worried about using iPods to share media between iTunes instances — something that seems quaint now. Today’s DRM infrastructure is much more robust.
 A common indicator of a sync problem. It’s so annoying that error details don’t appear in Console logs.