diff --git a/src/blenderbim/blenderbim/bim/module/material/operator.py b/src/blenderbim/blenderbim/bim/module/material/operator.py
index 9bc102c2ce..01ffc3cd22 100644
--- a/src/blenderbim/blenderbim/bim/module/material/operator.py
+++ b/src/blenderbim/blenderbim/bim/module/material/operator.py
@@ -157,7 +157,7 @@ class UnassignMaterial(bpy.types.Operator):
             self.file,
             **{"product": self.file.by_id(obj.BIMObjectProperties.ifc_definition_id)},
         )
-        Data.load(IfcStore.get_file(), obj.BIMObjectProperties.ifc_definition_id)
+        Data.purge()
         return {"FINISHED"}
 
 
diff --git a/src/ifcopenshell-python/ifcopenshell/api/material/unassign_material.py b/src/ifcopenshell-python/ifcopenshell/api/material/unassign_material.py
index 09c625a900..d01f3a78f8 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/material/unassign_material.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/material/unassign_material.py
@@ -1,4 +1,5 @@
 import ifcopenshell
+import ifcopenshell.util.element
 
 
 class Usecase:
@@ -9,11 +10,26 @@ class Usecase:
             self.settings[key] = value
 
     def execute(self):
+        if self.settings["product"].is_a("IfcTypeObject"):
+            material = ifcopenshell.util.element.get_material(self.settings["product"])
+            if material.is_a() in ["IfcMaterialLayerSet", "IfcMaterialProfileSet"]:
+                for inverse in self.file.get_inverse(material):
+                    if self.file.schema == "IFC2X3":
+                        if not inverse.is_a("IfcMaterialLayerSetUsage"):
+                            continue
+                        for inverse2 in self.file.get_inverse(inverse):
+                            if inverse2.is_a("IfcRelAssociatesMaterial"):
+                                self.file.remove(inverse2)
+                    else:
+                        if not inverse.is_a("IfcMaterialUsageDefinition"):
+                            continue
+                        for rel in inverse.AssociatedTo:
+                            self.file.remove(rel)
+                    self.file.remove(inverse)
+
         for rel in self.settings["product"].HasAssociations:
             if rel.is_a("IfcRelAssociatesMaterial"):
-                if rel.RelatingMaterial.is_a("IfcMaterialLayerSetUsage") or rel.RelatingMaterial.is_a(
-                    "IfcMaterialProfileSetUsage"
-                ):
+                if rel.RelatingMaterial.is_a() in ["IfcMaterialLayerSetUsage", "IfcMaterialProfileSetUsage"]:
                     self.file.remove(rel.RelatingMaterial)
                 if len(rel.RelatedObjects) == 1:
                     self.file.remove(rel)
diff --git a/src/ifcopenshell-python/ifcopenshell/api/project/append_asset.py b/src/ifcopenshell-python/ifcopenshell/api/project/append_asset.py
index 6c0668beb3..30c7bfa36c 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/project/append_asset.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/project/append_asset.py
@@ -11,7 +11,12 @@ class Usecase:
 
     def execute(self):
         self.added_elements = set()
-        if self.settings["element"].is_a("IfcTypeProduct") and not self.file.by_guid(self.settings["element"].GlobalId):
+        if self.settings["element"].is_a("IfcTypeProduct"):
+            try:
+                self.file.by_guid(self.settings["element"].GlobalId)
+                return
+            except:
+                pass
             return self.append_type_product()
 
     def append_type_product(self):