I am on the Andriod SE app on the Galaxy S2 when the problem appeared. I was on this question and upvoted the current posts at that time. For some weird reason, it doesn't show that I upvoted the question but does show that I upvoted the answer as shown:
As you can see, the upvote button will turn red when clicked, signifying that I did upvote the post. I thought that I might have undone the upvote, causing the red to disappear, so I tried upvoting it again. But at the top, it says "You have already voted on this question". Unknown vote now? Upvote button not red as normal now? Weird... So my question is, why isn't the upvote button red when I upvoted the question?
EDIT: It is not a duplicate because I posted my question 4 months before the duplicate arrived.