Sometimes because of a bad request there is an error when you press the vote buttons, so the vote isn't registered by the server, but the frontend still displays as a successful vote and adds to the total vote count. You can confirm this by refreshing the page and realize that your vote has disappeared. Also, because of this behavior you can't retry to vote on the same page until you reload it.
Could we change this behavior so on an error we still get the error message, but the vote isn't added in the GUI, so we can retry to cast a vote?
To test this behavior, just switch to offline mode, or unplug your Internet cable.