I updated iTunes to 12.1 and now weird things are happening with my iPad sync. I plug in the iPad and it shows all of the apps that are on it but when I click on "install" to add another app all my apps on the horizontal line at the bottom go away. It is like it wants to delete all the apps and then install only this one that I have selected. I don't want to take off all the apps just add a new one. What's up?