Instanced Static Mesh - Multiple Materials - Only draws in one eye in VR

[Oraclefish]

I’m working with instanced static meshes in UE 4.18 for a procedural map generator in VR, and if an object has multiple material channels, SOMETIMES, it will only draw one of the materials in one eye. Some objects work fine.

For example - I have an instanced static mesh map piece with two material channels.
One of the material channels draws in both eyes in VR.
One of the material channels draws in only one eye in VR.

I have another instanced static mesh map piece with two material channels, and both channels draw in both eyes.

Example image - the corner piece is incorrect (pink and panels are two separate material channels)
The other map pieces (the metal bars) are working fine with both material channels.

Does anyone have any ideas as to what could be causing this?
There is no difference in workflow for the different map pieces - I imported the .fbx files and applied the materials identically.

[Aidan_Puche]

Me too. And all the meshes all the same material base. Some identical Instances in another place works fine. I don’t know thats is the problem. Sometimes i broken the instance and rework again, and it’s see perfect.

[timtimmy]

Me too. I had to merge all of my meshes and materials to get them working with ISMC.