I managed to find my issue.

When creating a surface from contours, I did not realise the resulting entity is a group. So I was actually applying the texture to the group, rather than the actual surface. When I went into the group and directly applied to the surface, it worked properly.

I've created a reasonably large and detailed landform model from a set of 3D contours which I would like to texture with an aerial image.

However, when I apply the aerial using the projected texture method, only a small fraction of the landform faces actually become textured, see image below.

Does anyone know what would cause this issue and how I could be solved?

Cheers,
Dan.