Alexa flash briefing says "From...blah blah" then plays no content.

So I've got my content hosted in an amazon s3 bucket set to public read permissions. I've gone over the setup documentation many times. I've tried to make sure my audio file hits the recommend loudness and bitrate many times. I can't for the life of me figure out why my audio files won't play. I've downloaded a couple test files from other users and they work no problem.

Please see my json and audio file I'm trying to use as a test.

I've made sure my audio file loudness is between the recommended -14 to -19db with no loud peaks above -2db

https://s3.amazonaws.com/kaptainkoffee-flashbriefing/AlexaJson.json

https://s3.amazonaws.com/kaptainkoffee-flashbriefing/AlexaTest.mp3

What I hear from Alexa via echosim.io is "This is your flash briefing from KaptainKoffee test". Then I hear nothing, then Alexa says "that is all from your flash briefing".

So I know it's trying to play something, or at least looking for something.

Here is a test file I found on GitHub, that if I put the URL in my json file, alexa is able to play. I don't know what is different from my audio file:

https://raw.githubusercontent.com/okofish/flashtest/master/feeds/multiaudio-1.mp3

Please help! :-)

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