Why optimizing works on some cbots and not others including sample bots

Does anyone know why the platform will optimize on some cbots and not others? I have tried playing with sample cbots and works fine with optimizing. Come back the next day and it just gives clean passes with no results. Tried the same with other cbots from outside the platform. Had some good results with optimizing and now it just gives blank results when I go back and try to optimize again. Sitting here wondering what's happening. Any help would be appreciated. Thanks!