Comment this last line in the last cell:
# Display the results
display_artifacts(store, parent_artifacts, base_dir) # <-- comment this line
There is a bug in that method that tries to use the property id instead of artifact_id in the list of parent_artifacts. This creates an error which fails the whole submission grader. Someone at Coursera needs to go update the code in the util library and change the property name.
This will give you 110/120 points, but at least you will complete the assignment.