materials not working on gear vr

Hi,

I have previously created gear VR apps from UE4 without problems, but using the same process I am now finding my materials are not working - in the app they are rendered as ‘world grid material’.

I am applying baked lightmaps as emissive (unlit) materials. The meshes are created in sketchup and exported to blender where they are uv mapped and the textures baked. They have two uvmaps. They are imported to UE4 as FBX files, along with the lightmaps as PNG files, and the materials recreated there. I have tried this in both 4.10.4 and 4.11.2. The materials render fine in the editor. The test meshes are very small (38 tris).

Other materials in the standard ‘first person template’ are rendered fine in the app, but my meshes are not!

any ideas?

some more info: Im using a Galaxy S6 running Android 6.0.1.
and my PC is running windows 8.1 Pro

Ive just re-apk’ed an old file from v.4.11.2 and it works fine so the implication is that its something to do with my meshes…

strangely, changing the MIP settings on the textures from ‘fromTextureGroup’ to ‘NoMipMaps’ has solved this problem…

the textures were not in a separate folder, which also seems to be significant.

any more comments welcome, thanks