I just downvoted this question and then took it back, but I still have -1 rep, when I believe that it used to immediately give you the rep back. Is this a bug or do I have to wait for a rep recalc?
This is because you are over your daily rep cap. It's a bit of a bug in the system, but it prevents people from downvoting a bunch of posts early in the day, then reversing the downvote and gaining the rep back over the cap, so the system instead only gives back the 1 point if you're under 200.
If you want it back, you can request a rep recalc, but you may not like what you get (rep losses from deleted questions, etc)
I just downvoted your question and refreshed to confirm I lost 1.
Then I took it back and refreshed again, and I was back to what I had before.
The same thing happened when I tried it on the question you linked.