I was so frustrated by this issue today. I simply could not figure out why jQuery would return only 1 element for $("a") when I clearly had multiple anchor tags!
No matter what I did the length would always return 1.
I nearly missed the answer to the issue in a StackOverflow post. But it helped me find that jquery.validator was causing the issue. After going to the plug-in's website and downloading the latest version all was back to normal.
It's just unfortunate when you KNOW something is supposed to work right and you waste an hour trying to figure out why :(
Hopefully this post will help anyone with the same problem in the future and help them avoid any wasted time.