Failed to export node to file

I’m attempting to export multiple vtkMRMLTableNodes from an array to a directory

        for preset in self.presets:
            if preset and preset.IsA('vtkMRMLStorableNode') and preset.GetStorageNode():
                filename = presetsDir + '\\' + preset.GetName()
                if '.csv' not in filename:
                    filename += '.csv'
                slicer.util.exportNode(preset, filename)

But preset.GetStorageNode() continually returns None despite preset.IsA(‘vtkMRMLStorableNode’) being True. When I remove preset.GetStorageNode(), this shows up.

[Python] Failed to export node to file: C:\directory\...
[Python] Error: Unable to find a storable node with ID vtkMRMLTableNode1

However, the program successfully exports other table nodes that are in the subject hierarchy. I tried adding the tables I wanted to save to the hierarchy, but the issue persists.