here's the discussion on github.
i consider this a bug since the help says a bang "Starts open panel in current directory"
So until it gets fixed, you can try an external to get the current directory, although we've also had discussions that we should have such an object in vanilla. But again, you're still depending on it until anything happens.
I can suggest [else/dir] from my library
everyone else just uses [ggee/getdir], which is much simpler and just spits the directory
cheers