By default, it is disabled in tmux. It works fine in iTerm2's tmux integration mode, but not in plain old tmux. I'm hopeful that this feature will prove popular

By default, it is disabled in tmux. It works fine in iTerm2's tmux integration mode, but not in plain old tmux. I'm hopeful that this feature will prove popular and useful enough that I can get tmux to add support for it. To make it work in tmux integration mode just remove the check that $TERM == "screen" in $HOME/.iterm2_shell_integration.$SHELL.