Trying to edit a Python script node ends in me watching an endlessly spinning wheel for a while until losing patience after a few minutes and killing Revit via task manager. Happens like 1 out of 4 times, after restarting Revit and going straight for the edit it always works fine. Anyone else experiencing this? It’s getting quite annoying 
Which Revit version are you in? Fully updated? Check for a version conflict in your Dynamo logs to see if there’s a clue on the cause there. Also watch the ‘details’ tab in task manager when launching to see if anything spikes CPU use or RAM.
If you haven’t already, work in manual mode. Have had similar issues in automatic for Python nodes before.