diff --git a/cura/Machines/MachineNode.py b/cura/Machines/MachineNode.py
index 72652f2987..8d69ffdc8d 100644
--- a/cura/Machines/MachineNode.py
+++ b/cura/Machines/MachineNode.py
@@ -140,7 +140,7 @@ class MachineNode(ContainerNode):
             elif groups_by_name[name].intent_category == "default":  # Intent category should be stored as "default" if everything is default or as the intent if any of the extruder have an actual intent.
                 groups_by_name[name].intent_category = quality_changes.get("intent_category", "default")
 
-            if "position" in quality_changes:  # An extruder profile.
+            if quality_changes.get("position") is not None:  # An extruder profile.
                 groups_by_name[name].metadata_per_extruder[int(quality_changes["position"])] = quality_changes
             else:  # Global profile.
                 groups_by_name[name].metadata_for_global = quality_changes
diff --git a/cura/Machines/Models/BaseMaterialsModel.py b/cura/Machines/Models/BaseMaterialsModel.py
index 73d9d48b22..db660704b5 100644
--- a/cura/Machines/Models/BaseMaterialsModel.py
+++ b/cura/Machines/Models/BaseMaterialsModel.py
@@ -6,6 +6,7 @@ from typing import Dict, Set
 from PyQt5.QtCore import Qt, QTimer, pyqtSignal, pyqtProperty
 
 from UM.Qt.ListModel import ListModel
+from UM.Logger import Logger
 
 import cura.CuraApplication  # Imported like this to prevent a circular reference.
 from cura.Machines.ContainerTree import ContainerTree
@@ -153,7 +154,12 @@ class BaseMaterialsModel(ListModel):
         if not extruder_stack:
             return
         nozzle_name = extruder_stack.variant.getName()
-        materials = ContainerTree.getInstance().machines[global_stack.definition.getId()].variants[nozzle_name].materials
+        machine_node = ContainerTree.getInstance().machines[global_stack.definition.getId()]
+        if nozzle_name not in machine_node.variants:
+            Logger.log("w", "Unable to find variant %s in container tree", nozzle_name)
+            self._available_materials = {}
+            return
+        materials = machine_node.variants[nozzle_name].materials
         approximate_material_diameter = extruder_stack.getApproximateMaterialDiameter()
         self._available_materials = {key: material for key, material in materials.items() if float(material.getMetaDataEntry("approximate_diameter", -1)) == approximate_material_diameter}
 
diff --git a/tests/Machines/TestVariantNode.py b/tests/Machines/TestVariantNode.py
index 8ccde9bc74..9a0213ef99 100644
--- a/tests/Machines/TestVariantNode.py
+++ b/tests/Machines/TestVariantNode.py
@@ -139,9 +139,33 @@ def test_preferredMaterialExactMatch(empty_variant_node):
         "some_different_material": MagicMock(getMetaDataEntry = lambda x: 3),
         "preferred_material": MagicMock(getMetaDataEntry = lambda x: 3)  # Exact match.
     }
+    empty_variant_node.machine.preferred_material = "preferred_material"
 
     assert empty_variant_node.preferredMaterial(approximate_diameter = 3) == empty_variant_node.materials["preferred_material"], "It should match exactly on this one since it's the preferred material."
 
+##  Tests the preferred material when a submaterial is available in the
+#   materials list for this node.
+def test_preferredMaterialSubmaterial(empty_variant_node):
+    empty_variant_node.materials = {
+        "some_different_material": MagicMock(getMetaDataEntry = lambda x: 3),
+        "preferred_material_base_file_aa04": MagicMock(getMetaDataEntry = lambda x: 3)  # This is a submaterial of the preferred material.
+    }
+    empty_variant_node.machine.preferred_material = "preferred_material_base_file_aa04"
+
+    assert empty_variant_node.preferredMaterial(approximate_diameter = 3) == empty_variant_node.materials["preferred_material_base_file_aa04"], "It should match on the submaterial just as well."
+
+##  Tests the preferred material matching on the approximate diameter of the
+#   filament.
+def test_preferredMaterialDiameter(empty_variant_node):
+    empty_variant_node.materials = {
+        "some_different_material": MagicMock(getMetaDataEntry = lambda x: 3),
+        "preferred_material_wrong_diameter": MagicMock(getMetaDataEntry = lambda x: 2),  # Approximate diameter is 2 instead of 3.
+        "preferred_material_correct_diameter": MagicMock(getMetaDataEntry = lambda x: 3)  # Correct approximate diameter.
+    }
+    empty_variant_node.machine.preferred_material = "preferred_material_correct_diameter"
+
+    assert empty_variant_node.preferredMaterial(approximate_diameter = 3) == empty_variant_node.materials["preferred_material_correct_diameter"], "It should match only on the material with correct diameter."
+
 ##  Tests the preferred material matching on a different material if the
 #   diameter is wrong.
 def test_preferredMaterialDiameterNoMatch(empty_variant_node):