iTunes 12.... xxxx items could not be imported, see iTunes for more infomation

on syncing phone with iTunes (1st time since Yosemite/iTunes12 install) I see the following message 'xxxx items could not be imported, see iTunes for more infomation'

behold... iTunes has no additional information about what was and wasn't sync'd! Only half the library in a completely random manner - odd songs from albums.

What a a*** iTunes has become... it used to be so simple - you plugged in, ticked a few boxes and pressed sync - it worked. These days, it's like 10 times as long, involves a trip to www/forums, hair pulling, cussing and frustration and checking what iTunes has decided to do (or not to do!)

Anyone know why iTunes decides to sync some tracks off an album and not others?