amplify-js: UpdateEndpoint does not create Push Notification subscription

Describe the bug Running updateEndpoint from a React web application doesn’t actually create the endpoint in Pinpoint with the device token associated with it. It will not associate the Cognito user either.

To Reproduce The following code snippet, when run in a React web application (not React Native) succeeds, but does not send the channelType, address or userId to Amazon Pinpoint.

import { Analytics } from 'aws-amplify';

await Analytics.updateEndpoint({
    address: deviceToken,
    channelType: 'GCM',
    userId: this.props.user.username, // i.e. ferdingler
    userAttributes: {
        ...this.props.user // i.e. attributes like email and full name
    }
});

Expected behavior The previous code should update or create an endpoint in Amazon Pinpoint with the device token specified and linked to the userId provided. The following code snippet works correctly (this is not using Amplify):

const pinpoint = new AWS.Pinpoint({
    region: 'us-west-2',
    credentials: Auth.essentialCredentials(credentials),
});

const response = await pinpoint.updateEndpoint({
    ApplicationId: '4289.......f0d',
    EndpointId: uuid(),
    EndpointRequest: {
        Address: deviceToken,
        ChannelType: 'GCM',
        User: {
            UserId: this.props.user.username,
        },
    },
}).promise();

Desktop (please complete the following information):

• OS: macOS High Sierra
• Browser Chrome
• Version v71.x

Additional context The use case is about sending Web Push Notifications with Amazon Pinpoint -> Firebase Cloud Messaging and receiving them in a React web app using Amplify.

Taking a quick glance at the Amplify internal code, it seems that this is by design and not actually a bug. But it does feel like one. The documentation doesn’t warn that this cannot be run from a web app, and the fact that the call succeeds but ignores the data provided is misleading.

Any guidance will be very much appreciated.