Technical Rear seat belts buzzer odd behaviour. 2022 Fiat 500 Dolce Vita mild Hybrid

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Hi all, my daughters car appears to have a rear seat belt, occupancy fault?? or perhaps this is correct??

The seat belt buzzer goes off constantly until the rear seat belts are plugged in even when nobody is in the back.

Is this normal?
It has leather seats, not sure if standard or an optional extra on this car.

If you have a similar model what is the normal procedure with no rear occupants or seat belts plugged in, in the rear?

The front seem to work as expected, called Fiat and they say there are no occupancy sensors in the rear seats, if correct rules out a faulty sensor in the rear bench seat, but why would there be a buzzer on the rear seat belts if no occupancy sensor.

Cannot get to the car for another week to check anything, so just need info on how your car behaves.

Thanks