Material duplication after Reimport LOD

Editor Version: Version 4.2.1-2101290+++depot+UE4-Releases+4.2 (Dowloaded from Launcher), issue occur 100%


  1. Have a two models, SM_Box.fbx(lod 0), and SM_SP.fbx(lod 1)
  2. Import SM_Box.fbx as static mesh
  3. Open SM_Box in “Static Mesh Editor” in UE4
  4. Add new LOD from SM_SP.fbx
  5. Close “Static Mesh Editor” and place static mesh on scene.
  6. Select SM_Box in scene. SM_Box have a two material.
  7. Open SM_Box in “Static Mesh Editor” in UE4
  8. Reimport Lod 1
  9. Close “Static Mesh Editor” and select SM_Box in scene.
  10. Now SM_Box have a 3 material. If reimpoer again, 4 and more materials.

Also after reimport lod1 my Light Map Resolution reset to default 32, but before resolution is 128. Maybe other settings reset to, dont testing that.

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Thank you.

Hi BorodMorod -

Thank You for your help tracking this issue down, this is indeed a bug and I have entered it with our engineers.

Eric Ketchum

This bug still persists in Engine Version 4.7.6

Is there an update on this?

I believe the problem is that upon import the Default material is the world grid and not the BASE MESH Materials.

Hey -

Thank you for the report. We are still working on this issue. Since the new Material Slots are a Editor Glitch and do not create performance issues for games, it has been backlogged for a while. I have added your report to our issue and have asked we look into increasing the priority of this issue, but I still do not have an exact time table for any fix.

Thank You Again -

Eric Ketchum

Hey Eric,

It is good to hear it is just an editor glitch and does not affect performance. Most certainly should be backlogged. More important things to focus on that are engine specific. I appreciate your reply.


This still seems to be a problem in 4.9.2

Any suggestions on when it might be fixed, since it seems it has been a problem for one and a half year?

Hi Fjordhoj,

This is still backlogged. It’s not likely to be resolved soon due to other priorities. As previously mentioned this is just an editor glitch and does not affect performance.