Same here. I believe it was the 12.0.1 update. I specifically can recall seeing the descriptions in Yosemite last week, but not after the iTunes update. to 12.0.1.26 Also, on other forums, people are reporting the same problem with Mavericks and iTunes 12.0.1
So it seems it is iTunes, not the OS.
I am also very interested to see if anyone with Yosemite and iTunes 12.0.1 can see the descriptions. Maybe we can try to find common ground.
Also, I have already reported the issue with Apple. Recommend everyone to do the same.