By the way, I tried a Multiclass race with Class B and it works fine for me. I have selected max. available cars and it gives me about 40% class B cars.
Cheers Heiko, I think I've worked out the issue - if you have a custom AI file created for a particular series, it seems to stop multi-class racing. I've just deleted it and it appears I can now feast on multi-class goodness once again
You continue to fill in all the blanks with your top quality skins; and continue to make the game all the more immersive and enjoyable...Thank you for your ongoing efforts!! Well done!!