diff --git a/src/bonsai/bonsai/bim/module/geometry/operator.py b/src/bonsai/bonsai/bim/module/geometry/operator.py
index 7042789adb..d739c57c49 100644
--- a/src/bonsai/bonsai/bim/module/geometry/operator.py
+++ b/src/bonsai/bonsai/bim/module/geometry/operator.py
@@ -589,6 +589,7 @@ class UpdateRepresentation(bpy.types.Operator, tool.Ifc.Operator):
                     tool.Material.ensure_material_unassigned([element_type])
                 ifcopenshell.api.material.unassign_material(self.file, products=[product])
                 tool.Material.ensure_material_unassigned([product])
+                data = obj.data  # Required after ensure_material_unassigned
             else:
                 # These objects are parametrically based on an axis and should not be modified as a mesh
                 if extrusion := tool.Model.get_extrusion(old_representation):
diff --git a/src/bonsai/bonsai/tool/material.py b/src/bonsai/bonsai/tool/material.py
index 0139a1b783..dde9cc53d8 100644
--- a/src/bonsai/bonsai/tool/material.py
+++ b/src/bonsai/bonsai/tool/material.py
@@ -329,7 +329,10 @@ class Material(bonsai.core.tool.Material):
         or some other may be applied now since it's no longer overridden,
         therefore we need to make sure blender materials reflect correct styles.
 
-        Designed to be called after material.unassign_material API call."""
+        Designed to be called after material.unassign_material API call.
+
+        Will reload representations, invalidating existing object data.
+        """
         elements = elements.copy()  # Avoid argument mutation.
         for element in elements[:]:
             if element.is_a("IfcElementType"):