Can someone who works on current 737 models provide some information on the actual AOA sensors used? Some research on the subject shows that Boeing is using UTC made equipment on the 737.
I believe that they are based on a resolver principle
https://en.wikipedia.org/wiki/Resolver_(electrical) , in which case there will be two AC signals coming out of each AOA sensor forming a sine and cosine signal pair that must be put together to readout the angle.
Since both right and left sensors appear to have been following the AOA, but the left sensor had a 20 degree offset, the point in the aircraft where the sine-cosine signal pair are combined before digitizing would be where to look for the source of the AOA error. Loss of either of the AC signals would create a stationary AOA reading.
I know that this is a bit technical for most people, but it might bear fruit as to the likely source of the AOA malfunction. .