Cognito not being able to run ECS Task

[karkir0003]

@audionerd @matsev @sravimohan 'm trying to use JavaScript to run a task in ECS Fargate. AWS suggested to use Cognito Identity Credentials. When I pass in IdentityPoolId shown in:

import { fromCognitoIdentityPool } from "@aws-sdk/credential-providers";
import { ECSClient, RunTaskCommand } from "@aws-sdk/client-ecs";

const provider = fromCognitoIdentityPool({
  clientConfig: {region: "<region>"},
  identityPoolId: "<identity_pool_id>"
});

const ecs = new ECSClient({ region: "<region>", credentials: provider});

I get a message in the console like:

Uncaught (in promise) AccessDeniedException: User: arn:aws:sts::<accountid>:assumed-role/Cognito_<appname>Unauth_Role/CognitoIdentityCredentials is not authorized to perform: ecs:RunTask on resource: arn:aws:ecs:us-west-2:<accountid>:task-definition/<image-name>:<version> because no session policy allows the ecs:RunTask action

How do you resolve this issue. I'm looking at the activity in ECS and I see that the Unauth role did get assumed and it accessed ECS. It's just that the runTask doesn't work. Can someone provide example working code to solve this?