Thermador Dishwasher extra Softener not using Salt

I have a Thermador (sorry, Bosch was only dishwasher option in “Choose Your Device” section) that has a built-in water softener. It uses dishwasher salt. Recently, it stopped using any salt. (there is a setting - it is not programed to only use what it needs ). It should have required new salt in the last 3 months but it doesn’t which leads me to think it is not working. Any ideas to get it going again? The sensor that tells me to add salt is not lighting up. I tried pouring some in, but it is full.