Subject is Bosch dishwasher SHU6800.

Question

Subject is Bosch dishwasher SHU6800. There is a soap residue left on dishes. Residue is not visible. Using two glasses taken from a recently completed wash cycle I rinsed one under tap water and then filled glass with tap water. The second was just filled with tap water. There is noticeable soap bubbling and foam in the second glass. Starting the 10 min rinse/hold cycle following completion of a full 60 min wash cycle results in considerble soap foam in the bottom of the tub. Have tried three liquid dishwasher detergents and experimented with reduced detergent quantity. Same result. Does "rinse aid" material knock down the detergent? If so, could the quantity of rinse liquid address this problem? Thanks. JR