Onebox play button greyed out on attachment

Greetings friendly friends

I’m working with a voicemail forwarder that emails the .wav file to our community. I’m having some problems with the onebox: The file gets attached as .wav, so it is embedded in the post, and clicking allows download.
Copying the link into a new post creates a onebox as expected, but the play button immediately greys out. I presume this is a forwarder problem.
Is there any way to automatically display a player/onebox for certain file extensions attached to a post? Much simpler to display a play button than expect users to all download the file, play it, then come back to the browser.


New update seems to remove the download link for the .wav file and now we only see the non-working onebox player.

included markdown from the automatic attachment from the email post: