I ran a model with and without shading (overwriting the results) and the sDA result was the same each time. Therefore it looks like the sDA calc is not considering the shading. I tried adding the shading as a room, components and as local shading, each time the result was the same. The surface properties of the shading look sensible.
I even created a 100% shaded room, and the sDA results showed 100% sDA!!
I notice that the sDA 'Dynamic Simulation' is a beta, is this not fully implemented yet? However I see users below mention that shading was working for them so it's probably something silly I'm doing... Any ideas?