Race length problem in championship

Hi! I recently got AMS2 and I'm new to the forum! I've been really enjoying the game!

My issue is with a Stock Cars 2021 championship. I had set the race length to 25% to have 15 min races. But in the #7 race (second Interlagos race), it's a 60 min race no matter what setting I use!
Is it a bug? Intentional?

Thanks!