Hi Mike!
I see that the article says to change the script permissions with chown root:ossec. But since Wazuh version 4.3 the user and group were changed to wazuh. So, assuming that you are using version 4.3+ please try changing the scripts permissions with:
chown root:wazuh custom-shuffle
chown root:wazuh custom-shuffle.py
Let me know if this fixed your issue.
Regards!