Class "UInstancedStaticMeshComponent" deliberately leaves null pointers in the "InstanceBodies" array of FBodyInstances. This can be seen in methods such as:

[Engine\Source\Runtime\Engine\Private\InstancedStaticMesh.cpp]
UInstancedStaticMeshComponent::CreateAllInstanceBodies()
UInstancedStaticMeshComponent::SetupNewInstanceData()
UInstancedStaticMeshComponent::UpdateInstanceBodyTransform()

However, method UInstancedStaticMeshComponent::RemoveInstanceInternal() does not take this into account, and the following code crashes the engine by attempting to access such null pointers:

// Re-target instance indices for shifting of array.
for (int32 i = InstanceIndex; i < InstanceBodies.Num(); ++i)
{
InstanceBodies[i]->InstanceBodyIndex = i;
}

[Link Removed]

Vitor Barata 2023-10-19 03:32:14 UTC
Hi [~W014KNNASUF], I've got a JIRA report related to case 00633572.

• Open the engine and create a new level
• Create a blueprint and add a InstancedStaticMeshComponent to it. Set it up with any static mesh.
• In the ConstructionScript, EventBeginPlay, or any other event you can call in the Editor:
• Add a 1st instance with the default transform
• Add a 2nd instance with scale (0,0,0)
• Remove instance at index 0
• When running this code, the engine will crash on the removal