Multiple <app-indexeddb-mirror> not working when offline

[8ctopotamus]

I have two <app-indexeddb-mirror>s loading responses from two different <iron-ajax> calls. Both seem to work fine in build/bundled, until I take the app offline in dev tools or disconnect from WiFi.

Then only one of the dom-repeats, populated by its respective <app-indexddb-mirror>, renders on the page when I turn the network off, even though I can see the data from both responses in Dev Tools > Application > IndexDB.

<iron-ajax
      id="userData"
      url="api-url/users"
      handle-as="json"
      last-response="{{response_user}}"
      on-response="getUserDataComplete">
</iron-ajax>

<iron-ajax
      id="podcastData"
      url="api-url/podcasts"
      handle-as="json"
      last-response="{{response_podcasts}}"
      on-response="getPodcastDataComplete">
</iron-ajax>

<app-indexeddb-mirror
    key="userData"
    data="{{response_user}}"
    persisted-data="{{persistedUserData}}">
</app-indexeddb-mirror>

<app-indexeddb-mirror
     key="podcastData"
     data="{{response_podcasts}}"
     persisted-data="{{persistedPodcastData}}">
</app-indexeddb-mirror>

<!-- only this dom-repeat works in build/bundled when "offline" -->
<template is="dom-repeat" items="{{persistedUserData}}" as="user">
     <div>[[user.name]]</div>
     <div>[[user.slug]]</div>
</template>

<template is="dom-repeat" items="{{persistedPodcastData}}" as="podcast">
     <div>[[podcast.title.rendered]]</div>
     <audio src="[[podcast.acf.podcast_file]]" controls></audio>
</template>

Values in Dev Tools > Application > IndexDB:
key                      value
"userData"          Array[1]
"podcastData"    Array[10]

Any ideas as to why only one of the dom-repeats is rendering when offline?