app_url in the [app] capability is not for an enterprise signed build
You might have uploaded the non-enterprise signed app. The testing of features like Push Notification etc. require your enterprise signed app.
- Resign your app using the enterprise provisioning profile
- Upload your Enterprise signed app on BrowserStack
- Set the app capability in your tests, with the app_url returned (in the response of app upload)
- Set browserstack.resignApp capability (using this capability will disable resigning of your Enterprise signed 'app' so that you can test features like, push notifications on BrowserStack devices) to false
"browserstack.resignApp" : "false"