Problem: When running a conda environment and opening tmux on macOS, a utility called path_helper is running again. Essentially, the shell is initialized twice which messes up the ${PATH} so that the wrong Python version shows up within tmux.

Solution If using bash, edit /etc/profile and add one line. (For zsh, edit /etc/zprofile)

if [ -x /usr/libexec/path_helper ]; then
	PATH="" # <- ADD THIS LINE (right before path_helper call)
	eval `/usr/libexec/path_helper -s`