Validation issue during SageMaker Model Package Creation

Hello, I'm trying to share the SageMaker Model Package to marketplace so I needed to add CertifyForMarketplace=True and ValidationProfiles in my boto client call.

However in the end I got:

Profile name:
Client error: AlgorithmError: Model container failed to respond to ping. Please ensure /ping endpoint is implemented and responds with an HTTP 200 status code

This is weird because I'm pretty sure the same model package (without sharing to marketplace, i.e., the version without validation) works in both real-time inference and batch transform (since we added the ping endpoint in our custom container image).

Looks like other people are also running into it: https://github.com/aws/amazon-sagemaker-examples/issues/852

Any help is appreciated!

Thanks, Zac