Mandatory pitstop and crewchief

I was doing an AI race with Stock Car 24 with a mandatory pitstop.

Crewchief tells me the pit window is now open, I pit. Then a couple of laps later I see a GUI message in the game saying mandatory pitstop open.

When the race was finished I was DQd for not pitting.

Is this a bug somewhere ? or is there a way for crewchief to notify about correct mandatory pit window.

Thanks.

 

@projupiter When you set mandatory pit stops, the crew chief tells you that the pit is open on the first lap, which happens for any class in the game, but in the specific case of Stock Car and according to the actual rules, mandatory pit stops must take place within a window, e.g. from lap "x" to lap "y". You can make other pit stops outside this window, but you must still make one within this "window" and change at least one tire.