Trouble Selecting Random URL via Template

Hello All,

I have been having a hard time getting a particular automation working.
Specifically I cannot get the template below to respond as I expect it too.

I am using a Sonos to play wave files local on the HA server.
The automation fairly simple and tested to work fine without the template.
This leads me to believe I am missing something simple in the template.

If I manually set the media_player.play_media Media_content the automation works:

media_content_id: "http://192.168.#.123:8123/local/W01.wav"

Replacing the above URL with the below template throws errors.

Template:

          {%- set responses = [
          "http://192.168.#.123:8123/local/W01.wav", 
          "http://192.168.#.123:8123/local/W02.wav", 
          "http://192.168.#.123:8123/local/W03.wav",
          "http://192.168.#.123:8123/local/W04.wav",
          "http://192.168.#.123:8123/local/W05.wav",
          "http://192.168.#.123:8123/local/W06.wav"
          ] -%}
          {% set rindex =  (range(0, (responses | length - 1) )|random) -%}
          {{responses[rindex]}}

As soon as I add the template I begin receiving errors.
The template itself respond as expected in the template tester in Home Assistant.

Oct 06 23:15:12 PiMenu hass[31417]: 2017-10-06 23:15:12 ERROR (Thread-7) [soco.services] UPnP Error 714 received: Illegal MIME-Type from 192.168.##
Oct 06 23:15:12 PiMenu hass[31417]: self.handle_upnp_error(response.text)
Oct 06 23:15:12 PiMenu hass[31417]: File "/srv/homeassistant/lib/python3.4/site-packages/soco/services.py", line 469, in handle_upnp_error
Oct 06 23:15:12 PiMenu hass[31417]: error_xml=xml_error
Oct 06 23:15:12 PiMenu hass[31417]: soco.exceptions.SoCoUPnPException: UPnP Error 714 received: Illegal MIME-Type from 192.168.26.114
Oct 06 23:15:12 PiMenu hass[31417]: 2017-10-06 23:15:12 ERROR (Thread-7) [homeassistant.components.media_player.sonos] Error on play_media with UPnP Error 714 received: Illegal MIME-Type from ###

Full Automation

#############################################
## Sonos Door Chime
#############################################
- alias: 'Door Enter Chime'
  id: doorenterchime
  trigger:
    - platform: state
      entity_id: sensor.frontdoor_contact2_access_control
      from: '23'
      to: '22'
  condition:
    - condition: state
      entity_id: input_boolean.laser_trip
      state: 'off'
  action:
    - delay: '00:00:01'
    - service: media_player.play_media
      data:
        entity_id: media_player.office
        media_content_id: >-
          {%- set responses = [
          "http://192.168.#.123:8123/local/W01.wav", 
          "http://192.168.#.123:8123/local/W02.wav", 
          "http://192.168.#.123:8123/local/W03.wav",
          "http://192.168.#.123:8123/local/W04.wav",
          "http://192.168.#.123:8123/local/W05.wav",
          "http://192.168.#.123:8123/local/W06.wav"
          ] -%}
          {% set rindex =  (range(0, (responses | length - 1) )|random) -%}
          {{responses[rindex]}}
        media_content_type: "music"

Am I missing something on the template? Any help would be greatly appreciated.

Thanks!

Dustin H