In iTunes, click on your device and then click Sync. It will either complete really fast or it will get stuck on "Waiting for changes to be applied". You should notice on the upper left corner next to the name of your iDevice a triangle with a ! in it. Click on that it will generate an error code. Click OK and then resync. Should be fine after you acknowledge that it errored. If you don't it will continue not to sync. Had this happen with 3 of my iDevices in Mavericks. Once I did the above steps it started syncing them normally.