Executing multiple server functions in parallel

I'm having trouble understanding how to use the async: true flag in the createExecution function. Do I need to create some sort of queue system? I can't find any examples of how to do this for Cloud + Web (Node.js)

When I try to run the following function multiple times without async: true It's only running the first one. If I add async: true I get a server error: Error: Function execution failed with status 0:

  try {
    const execution = await functions.createExecution(
      "6667045d000c65a2ddcb",
      id,
      true
    )

    if (
      execution.responseStatusCode >= 200 &&
      execution.responseStatusCode < 300
    ) {
      return JSON.parse(execution.responseBody)
    } else {
      throw new Error(
        `Function execution failed with status ${execution.responseStatusCode}: ${execution.responseBody}`
      )
    }
  } catch (error) {
    console.error("Error fetching payment from server: ", error)
    throw error
  }
}

After playing around with some polling, I'm now getting an empty responseBody which might be tied to this issue: https://github.com/appwrite/appwrite/issues/6256

I guess I need to completely rethink they way I'm doing this