I cannot upvote or downvote any posts or comments.
Whenever I either upvote or downvote any post, sentence, or comment, my vote is not recorded. The page remembers whether or not I upvoted or downvoted, but the tally doesn't change to reflect my vote.
When I first vote, the tally does change. But if I refresh the page, my vote is no longer tallied. I have verified this by viewing posts with someone else's account to see if they can see my vote get counted, but it doesn't. In fact, that person's account had the same issue: their votes aren't counted either.
I noticed this a couple months ago. I reported the bug, but nothing has changed.