SLS_AWS_SDK_V3 - Unable to access SSM Parameters

[shaswot77]

The SSM Parameters though accessible via AWS CLI were not accessible using osls with AWS SDK V3 enabled and it works with it disabled. There are no issues with AWS Credentials and it was verified.
I am using AWS SSO than fixed credential.
Variables are referred like this in application - serverless.yaml

custom:
      secrets: ${ssm:/aws/reference/secretsmanager/dev-api-service, null}

Above usage led to this error

Cannot resolve serverless.js: Variables resolution errored with:

UnrecognizedClientException: The security token included in the request is invalid.

I have also seen similar issue reported with serverless - serverless/serverless#13182

[G-Rath]

I believe this is because SSO isn't supported yet so this is a duplicate of #87 (which'll hopefully be fixed via #88)

[shaswot77]

I have since tried with IAM user's access key and I have had no luck with it either.