Closing conversation with audio does not work with GH

[BoneGoat]

Closing the conversation with a media response works on a phone and in the simulator but does not work on a Google Home Device. The simple response is read out and the conversation closes but the audio doesn't start.

Steps to reproduce:

1. Create a DialogFlow project.
2. Set the Default Welcome intent to close the conversation with a MediaResponse card.
3. Add the required simple response and suggestions.
4. Add a Google Assistant integration.
5. Activate the simulator so the action can be triggered on a device.
6. Trigger the action on a Google Home device.

Observe that the action will start, speak the simple response and exit the conversation. The media response will however not trigger.

Using the SDK, the same behavior can be observed using: conv.close(MediaObject)

We have tested several different audio formats. Here's one for reference: https://static-cdn.sr.se/laddahem/podradio/mp/p3_dokumentar/2019/03/p3_dokumentar_20190331_1803_5cac6bbe.mp3