Hello Neil,
Thanks for reaching out! I appreciate you giving a detailed description of your experience.
It sounds like your colleague who left the business may have sent a copy of the course instead of transferring ownership to your other colleague. This explains the different Review link URLs. Can you try to reach out to your IT team to grant you temporary access to your old colleague's company email address? That way, you can access his/her Articulate account and change the password so you can access the course and transfer ownership.
Let me know how it goes, and I'd be more than happy to assist you further. If you want more targeted help, you can also connect with us privately in a support case.