Hmm, it’s quite possible something else is running- either in code or otherwise- that’s messing up the readings. I have a suspicion it could be some conflict between the sn3218 (that drives the LEDs) and the ADC, since they share the i2c bus and I seem to have been profoundly stupid here:
Which means that both of these threads are running simultaneously and potentially conflicting the bus.
If you get a moment, could you grab the code from GitHub, edit this file to remove the _auto_lights code, and install the library?
git clone https://github.com/pimoroni/automation-hat/
cd library
nano automationhat/__init__.py
Comment out the thread startup so it looks like:
#if is_automation_hat():
# _t_auto_lights = AsyncWorker(_auto_lights)
# _t_auto_lights.start()
And then install with:
sudo python setup.py install
And see if that fixes your ADC issues.