Inverting OpAmp non-symmetric output
You have a single supply ADC that cannot accept inputs outside supply rails +/-0.3V.

So you are overdriving the ESD protection diodes ( not good) which are Schottky at -1V.  which can cause shoot-thru latchup currents and damage IC from heat.


  Abs. Max= GND – 0.3.


You cannot get +/- 4.096 V input with a 3.3V supply.

You can use 3.3V supply , but you have to choose +/-2.096V range and change gain to   for your +/- 10V input signal and add a negative offset  to scaling OpAmp In-.  



Input -10.00V to + 10.00V
Output 0.000V to 2.000V +/- component tolerance stack error.
These values are available in 0.1%,0.05%,0.02% and 0.01%.