Reply disappears when voting
I'm sure I'm not the first person to notice it but I was unable to find it using the search. I don't know if it's a bug, but it is something I would like to see changed. If you click "reply" under a comment, and then vote on that comment, the comment box disappears. That would be fine if everything in the comment box didn't disappear with it. (This is also an issue when accidentally leaving a page, but that's an issue for another post.)
If you mean when replying to a forum post and up or down voting before posting your reply then yes it is the same (or similar problem) as leaving the page. But it is only a minor annoyance, just remember to post your reply before voting, or vote before writing your reply.