It happened to me only with people who were extremely, unreasonably cynical about people's rationality in the first place (including their own). People who couldn't update on the belief of people being unable to update on their beliefs. There's an eerie kind of consistency about these people's beliefs, at least for that much one can give them credit...

You have to engage in some extra signaling of having changed your own mind; just stating it wouldn't be as convincing.