Download and install the Archilab Bumblebee package and see if that works as another troubleshooting step.
If that fails, open the custom node up directly, grab the python node contained therein and copy it (ctrl+c), switch back to the main graph or close the custom node and paste the python node in. Wire in the inputs as needed and run the graph. Paste the error back here so we can learn if there is a difference.
As an alternative workflow in the meantime you can use a CSV.