I upgraded to 2018.3 to test some more and I also updated to your latest plugin as of what is available today.
When I import a .sbsar I get this Warning:
Identifier uniqueness violation: 'Gas_Storm - normal'. Scripted Importers do not guarantee that subsequent imports of this asset will properly re-link to these targets.
UnityEditorInternal.InternalEditorUtility:ProjectWindowDrag(HierarchyProperty, Boolean)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
The .sbsar then imports, but when I go to press the + icon to create duplicate instances I get the following errors:
InvalidOperationException: The object Gas_Storm - normal was already added to the context.
Substance.Editor.SubstanceImporter+<>c__DisplayClass61_0.<OnImportAsset>b__0 (UInt32 pOutputHash, Int32 pFormat, Int32 pChannelsOrder, Int32 pWidth, Int32 pHeight, Int32 pMipCount, IntPtr pPixels, Int32 pPixelLength)
Substance.Editor.SubstanceImporter.OnImportAsset (UnityEditor.Experimental.AssetImporters.AssetImportContext ctx)
UnityEditor.Experimental.AssetImporters.ScriptedImporter.GenerateAssetData (UnityEditor.Experimental.AssetImporters.AssetImportContext ctx) (at C:/buildslave/unity/build/Modules/AssetPipelineEditor/Public/ScriptedImporter.cs:20)
UnityEditor.AssetImporter:SaveAndReimport()
Substance.Editor.InspectorSubstanceBase:ApplyOrRevertChanges(Boolean)
Substance.Editor.InspectorSubstanceGame:OnInspectorGUI()
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
AssetImporter is referencing an asset from the previous import. This should not happen.
UnityEditor.AssetImporter:SaveAndReimport()
Substance.Editor.InspectorSubstanceBase:ApplyOrRevertChanges(Boolean)
Substance.Editor.InspectorSubstanceGame:OnInspectorGUI()
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
AssetImporter is referencing an asset from the previous import. This should not happen.
UnityEditor.AssetImporter:SaveAndReimport()
Substance.Editor.InspectorSubstanceBase:ApplyOrRevertChanges(Boolean)
Substance.Editor.InspectorSubstanceGame:OnInspectorGUI()
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
Asset import failed, "Assets/Procedural Planets/Materials/Gas/Gas.sbsar" > InvalidOperationException: The object Gas_Storm - normal was already added to the context.
Substance.Editor.SubstanceImporter+<>c__DisplayClass61_0.<OnImportAsset>b__0 (UInt32 pOutputHash, Int32 pFormat, Int32 pChannelsOrder, Int32 pWidth, Int32 pHeight, Int32 pMipCount, IntPtr pPixels, Int32 pPixelLength)
Substance.Editor.SubstanceImporter.OnImportAsset (UnityEditor.Experimental.AssetImporters.AssetImportContext ctx)
UnityEditor.Experimental.AssetImporters.ScriptedImporter.GenerateAssetData (UnityEditor.Experimental.AssetImporters.AssetImportContext ctx) (at C:/buildslave/unity/build/Modules/AssetPipelineEditor/Public/ScriptedImporter.cs:20)
UnityEditor.AssetImporter:SaveAndReimport()
Substance.Editor.InspectorSubstanceBase:ApplyOrRevertChanges(Boolean)
Substance.Editor.InspectorSubstanceGame:OnInspectorGUI()
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
UnityEditor.AssetImporter:SaveAndReimport()
Substance.Editor.InspectorSubstanceBase:ApplyOrRevertChanges(Boolean)
Substance.Editor.InspectorSubstanceGame:OnInspectorGUI()
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)
Here's the .sbsar I try to import:
https://www.dropbox.com/s/25929tpqdarvgye/Gas.sbsar?dl=0 - I have published it with the most recent version of Substance Designer.
After the error message above the substance no longer has a red substance icon or any children, but it's just a generic white icon and not recognized as a substance:
https://www.dropbox.com/s/0ab8upaqq6pmlvj/brokensubstance.PNGUpdate: I should also mention that that .sbsar has two normal maps that it generates, one with identifier "CapNormal" and the other one with identifier "BodyNormal".