Problem DTM '16 AI is pitting for fuel (so far) only on Norisring

I'm racing the AI with DTM '16 on various tracks in 55min + 1 lap races atm. To keep it as real as possible I'm using the 'mandatory pitstop' option in the race setup and I'm pitting once a race just for four new tires.
I've been to Hockenheimring, Lausitzring and Hungaroring so far and the AI did just the same as me (pitstop-wise) every race what was a great experience actually.
But today I went to Norisring with the same race setup and pit strategy and due to the pitstop I got from P8 to P1 because all the AI drivers pitted for fuel for about 17 seconds.

I wasn't able to find a way to avoid such behaviour, is there one that I can't see?
Or is this even kind of a bug and S3 doesn't want the AI to do so in such races and there might be a fix with a future patch?

 

Can you post race settings you were using ? Ai difficultly, how many ai , fuel and tyre wear multipliers or not etc , thanks

 

Of course, here you go:

 

If you select the DTM rules instead of the customers then the problem should be solved.

 

That did the job, thank you sir!