Seekable OCI (SOCI) push the index to ECR repo, Only SOCI index pushed, no image index pushed.

Hello, Does anyone encounter the issue (sudo soci push --user AWS:$PASSWORD xxxxxxxx.dkr.ecr.xxxx.amazonaws.com/xxxx:xxxxx) only push the soci index, not image index? From this doc https://aws.amazon.com/blogs/aws/aws-fargate-enables-faster-container-startup-using-seekable-oci/, there are two ways to create SOCI indexes for container image:

1. Use AWS SOCI Index Builder
2. Create SOCI indexes manually if i am Using AWS SOCI Index Builder (https://aws-ia.github.io/cfn-ecr-aws-soci-index-builder/), which is about Cloudformation stack would generates and pushes SOCI indexes to repositories in the Amazon ECR registry automatically. it will have soci index and image index

However, if i used the second way(create SOCI indexes manually), I can only see the soci index was pushed to ECR repo, no image index in ECR repo. Does anyone know why?