I think there is a bug in Content Manager. I have set complete Custom Championships, custom drivers with AI, liveries, and aggression set. I also set the tracks down to the actual weather on those dates in history. Everything works just fine and is amazing, until I exit Content Manager and come back later to resume my season.
Everything seems to be okay apart from the AI settings. The drivers no longer perform as I set once I load the custom championship season. One additional factor is that the slider prior to the race defaults to whatever the peak AI was in my previous set up to 100. I can adjust the slider down but either way (if I leave it untouched or move it down to a similar AI setting the AI do not perform as I inputted and saved).
If I start a new championship it will be fine again, everything working great, until I exit content manager and then whenever I boot it back up it has issues immediately no matter if I wait a few seconds or a few days.
Currently the only way around this issue is for me just to leave my computer running and content manager open until I complete the entirety of the championship.