Sometimes I walk into a Nether portal and it doesn't work. The screen gets all wavy, and then nothing happens. It just stays wavy. I don't change dimensions. This happens both ways, Nether to Overworld and Overworld to Nether.
I do not have Multiverse installed.
This occurs sometimes after I have just used the portal, and other times when I have not used a portal in a considerably long time.
I'm fairly sure this problem has something to do with my player.dat file, as removing the file and allowing the server to generate another fixes the issue temporarily.