Why isn’t occlusion culling working correctly?

Occlusion culling doesn’t seem to be behaving the way I was expecting. I’ve set the yellow wall as static and have baked an occlusion map using the occlusion window in unity. However when visualising the occlusion – the red cylinder behind the wall is still visible despite not being seen in the camera preview. Any clue what I’m doing wrong?Scene view with Occlusion culling visualisation