Problem description: only some songs that appear to be on the phone are playable. Many other song titles appear, but when I attempt to play them, the music skips to the next playable song, sometimes skipping past six or eight other songs, and the song that I originally tried to play now has a symbol similar to the one I normally see in the App Store when I am about to download the app. (It shows a thin circle around a square, all in red.)
. Note: I use a Windows 8.1 PC, not a Mac, to sync my iPhone 6.
. I have an iPhone 6, 128 GB, Space Gray.
. I had previously unchecked the box in iTunes that says 'automatically sync when this device is connected.' Now, it syncs only when I click 'Sync' or 'Apply' button, as the case may be.
. I had also previously performed a repair installation of latest iTunes version. I do not know whether that made any difference.
. I had also previously completely reset my phone, erasing all content and settings, and starting over. That solved the problem at the time, but it subsequently returned when I tried to add more songs to my phone.
Problem Solution:
Here is the exact order of the steps I took:
. I synced the phone without making any changes.
. (I would try skipping this step next time.) I disconnected the phone and deleted all of the music on the phone, using the Settings - General - Usage - Music - Delete approach on the phone itself.
. (I would try skipping this step next time.) I synced the phone again; that resulted in only 850 songs being copied to the phone, far short of the more than 4,000 songs that should have been copied.
. I disconnected the phone from the computer and iTunes.
. I reconnected the phone to the computer, and in iTunes, I unchecked 'Sync Music.'
. I synced again. That resulted in all of the music being deleted from the phone. Interestingly, all of the movies were recopied back to the phone. (I assume they were previously there, so that seemed strange to me. I had not clicked anything that should have affected the movies.)
. In iTunes, I checked 'Sync Music,' then clicked 'Apply.' That seemed to result in all of the music, more than 4,000 songs, being copied back to the phone.
. I have since confirmed that (probably) all of the songs I expected to find on my phone appear to be there, and are playable.
Of course, all of the syncing and resyncing took a long time, but at least all of my music was there.
One more comment: I have witnessed the 'waiting for changes to be applied' message being displayed for a long, long time. In my case, however, it subsequently appeared that something actually was happening while that message was displayed. In other words, although the message should have changed to something like 'copying,' or 'deleting,' those actions were indeed happening in the background. I was patient, and the 'waiting for changes' message eventually disappeared.
