I have found that when you are a certain range away from the AI Cars they become active again. Is this going to be fixed. And the races dont end they kind of just stop. There not post race menu.
Turn the option off before crossing the finish line...as for the AI not freezing after a while, i have noticed it too but it doesn't bother me since i have enough lead way...might be a problem for some though
There seems to be kind of a time limit to it. What I do is start the race with the option on. Be careful on your take-off, if you bump one of them they unfreeze. Get a few seconds away from them and deactivate the option. When they get too close then activate it again. Rinse, repeat.
It's a little tedious, yes, but it's better than trying to compete with perfect-driving, never crashing, instant max speed, perfectly tuned freaking AI cars.