2016 Volvo XC 70

Front right tire losing pressure. Low pressure sensor activating. Over course of 11 days, sensor activated multiple times.

Visit to Volvo dealership near place of work. Dealer could not find a leak in the tire. Tire was down to 11 psi. Dealer reinflated tire.

3 days later, sensor activated again.

Visit to different Volvo dealership closer to our home. Dealer could not find a leak. Will not dismount tire for further examination or replace tire under warranty absent finding a leak. Explanation is warranty requirements.

Any help on what to do would be appreciated. My wife drives my 4 and 8 year old children to school in this car.

Thank you.