Container-logs to s3

I have multiple apps running in shinyproxy on an EC2instance. I am using an IAM role to give my apps access to other AWS resources (e.g. s3, dynamodb, etc.) with no problems. However, I would like to write my container logs to a s3 bucket but can not seem to get it working. Following the shinyproxy configuration docs I have added the following to my application.yml file:

container-log-path: s3://my-bucket/shinyproxy-logs
container-log-s3-access-key: mykey
container-log-s3-access-secret: my_secret

For good measure I have also give access to the bucket to the host EC2 instance. But, while shinyproxy is working fine with these settings, nothing shows up in the s3 bucket. If I remove those settings and replace them with:

container-log-path: /etc/shinyproxy/container-logs

the logs do show up there. Am I missing something to get them to write to the s3 bucket?

I just wanted to bump this question again. Has anyone on here successfully set up per-container logging to s3? The documentation on how to do it is very clear and simple, but it does not work for me.