Here is something to try found in the Sync 3.4.20196 - Feedback & Issues thread.
louage
Can you try changing this AsBuilt as follows and see if it works? Please report back what this is currently set to on your vehicle:
tombailt
Works, thank You very much.
Changed 0 to 1
With 1 on 20196 front camera works The same as 0 or 1 in 20021 version. Zoom in rear camera works too