Data Action Lambda invoke returning 403 Forbidden despite correct IAM policy

Architect & Flows
1

Can’t get this config to load properly. Getting 403 when Architect Data Action calls Lambda.

  1. Created custom integration with https://lambda.ap-northeast-2.amazonaws.com/2015-03-31/functions/arn:aws:lambda:ap-northeast-2:123456789012:function:my-func/invocations.
  2. Set POST method. Body is `{}.
  3. IAM role has lambda:InvokeFunction permission.
  4. Response is 403 Forbidden with message “User: arn:aws:sts::123456789012:assumed-role/genesys-integration-role is not authorized to perform: lambda:InvokeFunction”.

Policy JSON:

{
 "Version": "2012-10-17",
 "Statement": [
 {
 "Effect": "Allow",
 "Action": "lambda:InvokeFunction",
 "Resource": "arn:aws:lambda:ap-northeast-2:123456789012:function:my-func"
 }
 ]
}

What is missing?