I think there is an alternative explanation to a WB issue.
It is important to remember that shadows are not neutral in colour: they are the colour of the light that falls on them. Usually this is hard to see, but if the surface in shadow is white it can be obvious. A common example is shadows on snow on a sunny day, which are blue-lilac because the shadow is lit by the blue sky light. Here is a famous example (Claude Monet, "Haystacks, Effect of Snow, 1891).
Looking at your images, I wonder if the green cast on the wall in shadow is not light reflected from the grass.