app-indexeddb-mirror with Polymerfire

I built a simple page that has multiple tabs. Each tab loads a feed (collection/list) of articles from Firebase and renders cards on the page. Everything works as I wanted until I tried to persist the visited feeds into indexeddb with app-indexeddb-mirror.

Here's what I did:

<dom-module id="my-view1">
<template>
    <style include="shared-styles">
    </style>

    <paper-tabs id="tabs"
                attr-for-selected="value"
                selected="{{selectedFeed}}"
                scrollable>
        <template is="dom-repeat"
                  items="[[feeds]]"
                  as="feed">
            <paper-tab value="[[feed.key]]">[[feed.name]]</paper-tab>
        </template>
    </paper-tabs>

    <firebase-query id="[[selectedFeed]]_feed"
                    app-name="myfirebaseapp"
                    path="/myfirebaseappdb/feed/[[selectedFeed]]"
                    data="{{articles}}">
    </firebase-query>

    <app-indexeddb-mirror
            key="[[selectedFeed]]"
            data="[[articles]]"
            persisted-data="{{persistedArticles}}">
    </app-indexeddb-mirror>

    <template is="dom-repeat"
              items="[[persistedArticles]]"
              as="article">
            <paper-card image="[[article.image]]" alt="image">
                <div class="card-content">
                    <h1 class="card-text">[[article.title]]</h1>
                    <h4 class="card-text">[[article.abstract]]</h4>
                </div>
            </paper-card>
    </template>

</template>

<script>
    Polymer({
        is: 'my-view1',
        ready: function () {
            this.feeds = [
                {name: "Feed1", key: "feed1"},
                {name: "Feed2", key: "feed2"},
                {name: "Feed3", key: "feed3"},
                {name: "Feed4", key: "feed4"}
            ];
        }
    });
</script>

What I want to do is cache each feed into indexeddb as an entry (feed name as key and the data as value), so they can be loaded when the app is offline. That's basically what app-indexeddb-mirror is for, right?

However I cannot get my head around the data flow between firebase-query and app-indexeddb-mirror, and I keep getting indexeddb entry overwritten/emptied when switching tabs.

Is there something I am not doing right? Thanks.

I solved this issue by swapping firebase-query and app-indexeddb-mirror. I never knew sequence matters in Polymer, also this order is quite counter-intuitive.