Storybook: El panel de complementos no se muestra, pero las perillas aún funcionan (?)

Describe el error
Estoy usando el complemento de perillas para mi proyecto StencilJs y técnicamente está funcionando (si configuro el problema del componente dentro de la historia, lo está cambiando, por ejemplo: mire el archivo de la historia y luego el componente, verá que está configurando eso - y lo hace). pero no puedo ver el panel de complementos. Creo que he hecho toda la configuración correctamente (addons.js, package.json, etc.).

Intenté seleccionar la opción de mostrar complementos dentro del libro de cuentos en ejecución, pero no se muestra nada.

Cómo lo estoy ejecutando es con npm run storybook

Reproducir
Pasos para reproducir el comportamiento:

1. Lanzar libro de cuentos
2. Ningún panel de complementos es visible en el lateral o en la parte inferior

Comportamiento esperado
Espero ver el panel de complementos si tengo un complemento instalado para ser utilizado

Capturas de pantalla

Fragmentos de código
A continuación se muestra mi .storybook / addons.js

import '@storybook/addon-a11y/register';
import '@storybook/addon-actions/register';
import '@storybook/addon-knobs/register';

A continuación se muestra mi package.json

"scripts": {
    "build": "stencil build",
    "start": "stencil build --dev --watch --serve",
    "stencil.dev": "stencil build --dev --watch --docs",
    "storybook.dev": "./node_modules/.bin/start-storybook -p 8008 -c .storybook -s ./dist",
    "storybook": "npm run build && ./node_modules/.bin/concurrently  \"npm run stencil.dev\" \"npm run storybook.dev\"",
    "test": "stencil test --spec --e2e",
    "test.watch": "stencil test --spec --e2e --watch",
    "generate": "stencil generate"
  },
  "dependencies": {
    "@ionic/core": "^4.9.1"
  },
  "devDependencies": {
    "@stencil/core": "^1.7.0",
    "@stencil/less": "^1.0.0",
    "@stencil/utils": "0.0.5",
    "@stencil/webpack": "0.0.6",
    "@storybook/addon-a11y": "5.2.3",
    "@storybook/addon-actions": "5.2.3",
    "@storybook/addon-knobs": "5.2.3",
    "@storybook/addon-storysource": "5.2.3",
    "@storybook/addon-viewport": "5.2.3",
    "@storybook/addons": "5.2.3",
    "@storybook/cli": "5.2.3",
    "@storybook/html": "5.2.3",
    "@storybook/polymer": "5.2.3",
    "babel-core": "6.26.3",
    "babel-loader": "7.1.5",
    "babel-preset-env": "1.7.0",
    "lit-html": "1.1.1",
    "polymer-webpack-loader": "2.0.3",
    "ts-loader": "^5.4.5",
    "concurrently": "^4.1.0"
  }

A continuación se muestra mi .storybook / config.js

import { addDecorator, addParameters, configure } from '@storybook/polymer';
import { withA11y } from '@storybook/addon-a11y';
import { withKnobs } from '@storybook/addon-knobs';
import 'sumai-frontend';

addParameters({
  options: {
    /**
     * name to display in the top left corner
     * <strong i="6">@type</strong> {String}
     */
    name: 'Sumai Components',
    /**
     * URL for name in top left corner to link to
     * <strong i="7">@type</strong> {String}
     */
    url: '#',
    /**
     * show story component as full screen
     * <strong i="8">@type</strong> {Boolean}
     */
    isFullscreen: false,
    /**
     * display panel that shows a list of stories
     * <strong i="9">@type</strong> {Boolean}
     */
    showNav: true,
    /**
     * display panel that shows addon configurations
     * <strong i="10">@type</strong> {Boolean}
     */
    showPanel: true,
    /**
     * display floating search box to search through stories
     * <strong i="11">@type</strong> {Boolean}
     */
    showSearchBox: false,
    /**
     * show addon panel as a vertical panel on the right
     * <strong i="12">@type</strong> {string}
     */
    addonPanelInRight: true,
    /**
     * sorts stories
     * <strong i="13">@type</strong> {Boolean}
     */
    sortStoriesByKind: false,
    /**
     * regex for finding the hierarchy separator
     * <strong i="14">@example</strong>:
     *   null - turn off hierarchy
     *   /\// - split by `/`
     *   /\./ - split by `.`
     *   /\/|\./ - split by `/` or `.`
     * <strong i="15">@type</strong> {Regex}
     */
    hierarchySeparator: null,
    /**
     * regex for finding the hierarchy root separator
     * <strong i="16">@example</strong>:
     *   null - turn off multiple hierarchy roots
     *   /\|/ - split by `|`
     * <strong i="17">@type</strong> {Regex}
     */
    hierarchyRootSeparator: null,
    /**
     * sidebar tree animations
     * <strong i="18">@type</strong> {Boolean}
     */
    sidebarAnimations: true,
    /**
     * id to select an addon panel
     * <strong i="19">@type</strong> {String}
     */
    selectedAddonPanel: undefined, // The order of addons in the "Addon panel" is the same as you import them in 'addons.js'. The first panel will be opened by default as you run Storybook
    /**
     * enable/disable shortcuts
     * <strong i="20">@type</strong> {Boolean}
     */
    enableShortcuts: true // true by default
  }
});

const req = require.context('../src/components', true, /story.tsx$/);
function loadStories() {
  req.keys().forEach(filename => req(filename));
}
configure(loadStories, module);
addDecorator(withA11y);
addDecorator(withKnobs);

// HMR interface
if (module.hot) {
  // Capture hot update
  module.hot.accept('sumai-frontend', () => {
    document.location.reload();
  });
}

a continuación está mi historia.tsx

import { storiesOf } from "@storybook/polymer";
import { text } from "@storybook/addon-knobs";

storiesOf("Basic Components", module)
  .add("Modal", () => {
    const el = document.createElement("sumai-full-width-image");
    el.name = text('Name', 'Namey');
    return el;
  });

Sistema:

System:
    OS: Linux 5.0 Ubuntu 19.04 (Disco Dingo)
    CPU: (4) x64 Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz
  Binaries:
    Node: 10.15.3 - /usr/local/bin/node
    Yarn: 1.16.0 - /bin/yarn
    npm: 6.4.1 - /usr/local/bin/npm
  Browsers:
    Chrome: 75.0.3770.80
    Firefox: 69.0.2
  npmPackages:
    @storybook/addon-a11y: 5.2.3 => 5.2.3 
    @storybook/addon-actions: 5.2.3 => 5.2.3 
    @storybook/addon-knobs: 5.2.3 => 5.2.3 
    @storybook/addon-storysource: 5.2.3 => 5.2.3 
    @storybook/addon-viewport: 5.2.3 => 5.2.3 
    @storybook/addons: 5.2.3 => 5.2.3 
    @storybook/cli: 5.2.3 => 5.2.3 
    @storybook/html: 5.2.3 => 5.2.3 
    @storybook/polymer: 5.2.3 => 5.2.3

Contexto adicional