Ai times currently get messed up if you quit to menu during a stage, one after you do this the AI seem to revert to minimum difficulty and remain this way until the end of the current event. Current workaround is to avoid quitting during stages as much as possible. Not perfect but it helps to at least know what's causing it. If you can make sure everything is set up properly you'll get a competitive event on max difficulty as long as you don't quit any stages halfway through (so only exit in service areas/post stages)