Imported linked blocks Render differently when exploded

Hi all,
When importing a linked block into a model, it seems to bring across with it its own lighting/sun direction setting so when it is rendered the textures are shadowed on one side as if the sun is behind them.

The sun is switched off on the block and switching the sky on/off makes no difference.
When exploding the block, the issue is resolved, however we need to retain the items as linked blocks.

Images below show the issue. Both renderings done in the same file, same model, before and after exploding the linked block. Is there a way to instruct Rhino to override any block lighting settings during rendering?

Rhino 6, Flamingo nXT 5.5

Is there a setting to ignore global lighting within blocks?

Looks like surface normals are rendered wrong, like flipped.

Yes, although the issue only seems to become apparent when I rotate the blocks to something other than their initial placement, as if the somehow remember the lighting (or copy a setting from their linked location).

Are the objects NURBS or meshes? I would check the normals at the linked block. Is the block mirrored?

In the past I got surface normal issues at mirrored blocks. Surface normal issues could cause that a concave surface looks like a convex surface.

Hi @Micha
The blocks are NURBS and not mirrored, just imported as per their previous saved state.
Once rotated, the shading on them appears inverted, as if the object is hollow. This looks most apparent on cylinder shapes. Even does it on simple shapes with no materials applied…