Fix the using of protected property in CustomQualityProfilesModel

cura/Machines/Models/CustomQualityProfilesModel.py

@@ -12,7 +12,7 @@ class CustomQualityProfilesModel(QualityProfilesModel):
     def _update(self):
         Logger.log("d", "Updating %s ...", self.__class__.__name__)
 
-        active_global_stack = Application.getInstance().getMachineManager()._global_container_stack
+        active_global_stack = Application.getInstance().getMachineManager().activeMachine
         if active_global_stack is None:
             self.setItems([])
             Logger.log("d", "No active GlobalStack, set %s as empty.", self.__class__.__name__)