Cannot plant crops underground

I just noticed, during the 1.5 update release, that most of my crops such as wheat, potatoes, and carrots have disappeared from my underground farm. The must of broke off the ground and vanished after a time. I tried planting some new ones, but I noticed that, when I placed some next to each other, they fell off. I tried doing this on Creative mode, but they managed to stick to each other. They even sounded like I was placing stone blocks as well.