Issue with importing alembic files: the skeletal mesh asset doesn't contain LOD description

Helloo everyone!! 😄

We are experiencing an issue with importing skeletal meshes from alembic. For reference, this issue happens in vanilla engine 5.7.4, but it doesn't occur in versions 5.6.x.

1) After importing an alembic the skeletal mesh asset doesn't contain LOD description. Just after the import when we want to open/use the asset we have a crash on FSkeletalMeshModelingToolsEditorModeToolkit::OnEditorModeInitialized.

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The AssetLODModes array is empty. 

2) When we save the skeletal mesh asset and then after restart of the editor we want to load the asset it is trying to recover LOD info on the post load step of the asset l*oading(PostLoadRecoverConvertLODModelsToMeshDescription)*.

In most cases, it causes memory overflow and crashes the editor. The worst thing is that the recovery process is running without any prompt to the user. We have only a “Waiting for skinned asset to be ready 0/1” task popup and we have no option to skip it or trigger the LOD rebuild manually, after the recovery also looks like the asset is not marked as dirty and the process can be repeated after each restart of the editor.

The problem escalates because any load of the asset (our internal tools, validators or even native Unreal tools) triggers this time and memory consuming process of LOD recovery.

The callstack of time and memory consuming task:

UnrealEditor-SkeletalMeshDescription.dll!TMeshAttributeArrayBase>::Insert(const int Index, const UE::Math::TVector & Default) Line 192 C++ UnrealEditor-SkeletalMeshDescription.dll!TMeshAttributeArraySet>::Insert(const int Index) Line 422 C++ UnrealEditor-Engine.dll!FAttributesSetBase::Insert(const int Index) Line 1769 C++ UnrealEditor-Engine.dll!FMeshElementContainer::Add() Line 82 C++ [Inline Frame] UnrealEditor-Engine.dll!FMeshDescription::CreateVertex() Line 206 C++ UnrealEditor-Engine.dll!FSkeletalMeshLODModel::GetMeshDescription(const USkeletalMesh * InSkeletalMesh, const int InLODIndex, FMeshDescription & OutMeshDescription) Line 1440 C++ UnrealEditor-Engine.dll!USkeletalMesh::PostLoadRecoverConvertLODModelsToMeshDescription() Line 3690 C++ UnrealEditor-Engine.dll!USkeletalMesh::ExecutePostLoadInternal(FSkinnedAssetPostLoadContext & Context) Line 4085 C++

3) Import options mostly default, unchecked Bake Matrix Animation

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We are currently experimenting with different Alembic export/import options to find a solution. However, we would greatly appreciate any guidance or assistance you can provide us.