ADC1 on sensor_vp (IO36) not working as expected

[amarotica]

Hi all,
I am trying to analogRead GPIO 36 on an ESP32-WROOM-32UE module. GPIO is also known as sensor_vp, on ADC1.
For some reason, every reading gives me a value of 4095 with my current setup.
I initialize the GPIO with pinMode(36, INPUT); then read with int reading = analogRead(36);

Reading the voltage of the pin with my Fluke gives me 0.39v, so the reading should be roughly 495 at default settings.
My connections are as follows:
ESP32 sensor_vp <--> bus
Ground (ESP32) <--> 47k ohm <--> bus
8.4v (same gnd ref) <--> 330k ohm <--> bus
12v (same gnd ref) <--> 330k ohm <--> bus

Can anyone think of a reason this wouldn't work properly? When I load the bus down to ground with a 220 ohm resistor, it reads low, but with the current setup it doesn't read anything other than 4095.

Thanks for any ideas you might have.

I do not use the hall sensors, and WiFi isn't turned on until after the adc readings take place. Is there any other functions that would affect this?