I think I have found the issue(s)

the repo that we had for our images was "xyz.com". It worked great getting the image list, but failed with the above error when performing a "list_tags" for images in that repo.

Not sure if the repo name is "valid" and there is an issue in the api, or the repo name needs to be changed.
The process worked flawlessly with repos without a "." in the name.

Thank you for your help and responses :)