After opening a ticket with Support, I think that I figured out the issue myself.
Symptom: I was executing a python script via the python tool, but no output was displaying.
I tried changing from Interactive to Production and saw a message that included my temp directory (on drive d:). I found another problem, you can't run production mode if you're using a d: temp drive. At least that was my error message interpretation.
Resolution: Change your temp directory to C: to get the python tool to output data. That isn't going to work for me or my clients as we don't write to the C: drive.
Cheers,
Mark