Materials all mixed up on some parts of mesh after importing

[WF_Bart]

I’m trying to import a model from Blender to Unity. Unity created the materials as expected, but messes them up on some parts of the model; particularly the interiors I’ve made.
It does seem to have the right materials on the mesh, but they’re switched around for some reason and I can’t figure out what makes this happen and why it only happens to some parts of the model. In Blender everything seems fine.

Here you see the materials of the deckhouse_interior mesh… Please note that this was imported at the same time as the exterior, including e.g. the lifeboat top-left, which all have the materials correctly applied.
Deckhouse_Interior and the mesh that’s at the bottom of the stairs both have their materials screwed up though.

As an example you can see ‘Ship_carpet’ as element 1, where that should actually be element 7! The same goes for all the other materials on the mesh.

This is what the model looks like in Blender (I’ve removed the deckhouse exterior mesh so you can look inside in both examples).

Why does this happen and how I do stop it?

[WF_Bart]

Okay, I’ve found the problem. This happens when a part of the mesh has no material assigned to it. Unity creates a duplicate material with a duplicated name and messes up the order in which the materials are assigned.

After identifying and removing the piece of untextured material, the mesh imported correctly.

Is this behaviour of Unity intended?
If a mesh has no material assigned to it at all, Unity creates an ‘unnamed’ material, which is rather more helpful.

[cgworkers]

What i found the unity material system works in an Alphabetic order i found a tutorial hope this would help

how to extract materials from blender to unity

Plus if you add textures in unity before imparting the fbx in unity assets it usually picks the texture in unity