Thank you for the response! Unfortunately, even with the maximum and minimum, the problem persists.
328P datasheetThe ADC converts an analog input voltage to a 10-bit digital value through successive approximation. The minimumvalue represents GND and the maximum value represents the voltage on the AREF pin minus 1 LSB.Optionally, AVCC or an internal 1.1V reference voltage may be connected to the AREF pin by writing to the REFSnbits in the ADMUX Register. The internal voltage reference may thus be decoupled by an external capacitor at theAREF pin to improve noise immunity.