I'm led to believe it's Apple's fault as they have discovered that various sources throughout the world download their music via an illegal source (i.e. YouTube to MP3 converters).
If this is the method you use, then no matter how many times you right-click on a song in "My Music", click 'Get Song Info' and enter in the correct song information, iTunes refuses to re-hash the information for your selected song.
Ever since Apple's iTunes 12 overhaul, users who condone third-party download sites have been affected.
The only way people such as you and I can fix this problem is to either purchase our music from the iTunes Store or subscribe to Apple's "Music Genius" promotion -- at a cost of $34.99 annually.
I'll pass, thanks. As for now, I prefer to use my older mobile device to 'drag and drop' .mp3 files -- back when it was oh so much easier!