User blog comment:Niceperson/The most weirdest thing ever,,,/@comment-5321651-20141231065421

Are you using the same browser as always? This sometimes happens to me. If I log into my account on Firefox, then go on Chrome, I won't be automatically logged in. But then if I log in on Chrome and then go back onto Firefox, I won't be automatically logged in on Firefox because of Wikia safety rules. Also, when you log in, make sure you have that little box that says "Never log me out" or something, because if you don't have that ticked, it won't happen.

If the cause is still unknown then try what Tupka217 said and contacting Wikia about your bug :)