I've switched to using GPIO3 and confirm all working! Thanks again.

Awesome! Thank you so much @boarduz for pointing this out, I was pulling my hair out last night. Lesson for me is to exercise more caution over using the strapping pins (2,8,9) and to go back to the schematic. This is only the second board I've used so lots to learn.

I'm using a DFRobot ESP32-C3 and want to monitor it's battery voltage using ADC1 GPIO 2. The circuit for connecting up GPIO2 is a voltage divider and a capacitor. I've verified the resistor values with a multimeter and tested for continuity. The problem is that despite the supply into the top of the...