I recently had the same problem while using WordPress 4.9.2 and ACF 5.6.7 with Genesis 2.5.3 on a MAMP 3 localhost development site. I attempted to embed two mp3 URLs and all I got on the front end was what appeared to be a raw shortcode.
[audio src="..."/]
James’ solution worked, but it took me a while to find it. It’s the first glitch I’ve had with ACF Pro, which otherwise works perfectly and is exceedingly well documented.
If this is a recurrent problem, though, perhaps an adjustment to the OEmbed field code is needed. Or, in the meantime, you might copy this code to the documentation page. It might save some other people some time.
