I have a basic Serverless Express app in a lambda, with a route set to async true. I want to trigger this route asynchronously from a different application, and expect it to run in the background without having to wait for the response.

The route in serverless.yml

- http:
    path: foo/{any+}
    method: post
    async: true
- http:
    path: another/sync-route
    method: post

Note: I have other routes in here that are not invoked asynchronously.

When I call this method, it correctly returns a 200 response immediately. But the actual code is never run, I have a DB insert in there, and it doesn't happen. In the API Gateway I can see the X-Amz-Invocation-Type header is correctly being passed as Event type.

What am I missing here? The route controller is a test and the code is very simple

 testAsync: async (req, res) => {
    console.log("In Test Async");  // Does not display in Cloudwatch
    try {
      const { value } = req.body;
      const resp = await updateTest(value);  // This just inserts an entry in the DB with value
      return res.send(resp);
    } catch (err) {
      return res.status(500).send(err);
    }
  },

Is there any other setting I'm missing here? I'm not an AWS expert, so any help would be highly appreciated. Thanks!