Comment by t_mahmood

I had it, but it was not working.

BUT I got it to work! Apparently I had my tmux setup wrong

Changing to this fixed the colors on tmux. Hopefully this help someone in the future.

    # tmux colors
    set -g default-terminal "xterm-256color"
    set -ag terminal-overrides ",xterm-256color:Tc"

Got it from here https://github.com/vim/vim/issues/3608#issuecomment-84907404...