My iPhone does not sync with my MBA any longer
Since a couple of days my iPhone does no longer sync with my MBA. I can't upload music from my MBA to my iPhone 5s with iTunes. When I select or deselect music the info bar, showing the used space from my iPhone displays nonsense numbers. When I deselect(!) music it shows 12GB free space. When I select music, it shows 19GB free space. This happens before and after(!) update to latest version of iTunes. Is that an iPhone or Macbook Problem? How to fix it?
MacBook Air, OS X Yosemite (10.10.4), null