I have the Switchdoc grove connector hat and the Switchdoc ADC/ADS1115 running on a raspberry pi zero w.
I have an analog light sensor hooked to the ADC A1 port and it works fine
I have the two capacitive soil moisture sensors hooked to the ADC, one is using A0 on the pins and one is using the grove A2 port. Neither are generating voltage to the rPi.
When I move the moisture sensor's VCC from the VCC pin on the ADC to the 3.3v pin on the pi it starts to generate voltage, but it's unreliable (it moves very slowly in the correct direction, but takes 40+ seconds to get to the correct reading).
If i add a 1M ohm resistor between the Analog and GND it works as expected.
edit: maybe this sensor is not built properly. here's someone else with a similar problem