So, huh, guess what? I'm doing exactly that! And was doing exactly that the first time!So, huh, make sure you launch the 3.3 Horizons beta. Not just the 3.3 beta.
Cause krait phantom and mamba are both at Jameson Memorial.
Restarted the game, just to be sure (you never know, huh?) - nope, still 37 ships and no Mamba.