Correct function of the belt warning device on the rear row of seats (XC60)

Hello together, I have a question about the function of the belt alarm on the rear row of seats. I believe that this safety feature does not work properly with me. 1. Situation: Passengers get in the back and do NOT buckle up. I start the engine and start driving. Result: Display in the instrument cluster that no belt is used. However, NO warning tone is issued. 2. Situation Passengers get in the back and fasten themselves. I start the engine and start driving. Passengers buckle down during the ride. Then he descends and I continue driving. Result: Display in the instrument cluster that the belt is used at the rear right. With the warning (warnton) the warning is made that no belt is used. Even after getting out, the warning tone does not go out. I can either close the belt without the driver (which is not particularly wise at all) or make the car short. Question: Is this also so with you? Or do the rear warners react to you just as before? Many greetings Andreas