Do they go away over time? Tested here and not getting them but what I did notice is that IR has a max amount of passes (8) and wondering if perhaps you aren't changing something before those passes are reached, Corona begins to redraw using the new values, but some parts of the image reach 8 passes and so then IR stops, leaving half the image updated, half not.
What happens if you set Max passes for IR to 0 and let Corona continually redraw the image? For me, it makes those clear up over time (I got them to show up by detaching and reattaching the Corona Wire to the Diffuse of the material - but once IR was not set to stop at 8 passes, those just cleated up quickly over time).