rdInst Tutorial 31 – Building HLODs with prefabs
By default, when building HLODs when using Instanced Static Meshes or ChildActors, they will be missed from the build.
To overcome this, rdBPtools has tools built in to convert the prefab to using StaticMeshComonents for all instances – the HLOD can be built using those, then the prefab can be converted back to using instances.
You can convert multiple prefabs at once by selecting all you want in the HLOD and using the context menu.
Visit This Link to see a full tutorial on creating HLODs.