iPad Can't export all photo's to iPad (from pc)

Hi there!

I restored my iPad Air 2 128GB in DFU modus to iOS 9.3 (comming from 9.2.1). I have like 100GB of photo's and video's on my pc that I always use on my iPad.

So I tried to export all files again but not all files are being uploaded to the iPad (from the newest version of iTunes). What's wrong?

I already deleted the iPod Photo Cache. Restarted PC, turned off virus scanners etc. But there are still files (over 20GB) that are not exported to my iPad.

iPad has like 30GB free space atm so that's not the problem and it has never been a problem till yesterday.

Can someone help me?

 

No one who can help me?