Have just tested this on a blog here and see the issue - the editor is messing with it. I'd recommend using the "Embed Local Media" button in the editor if you want to embed something, although I know that does not give you access to the "search" option. I'll see if there's a workaround or not. In the meantime you could just make a custom playlist for a bunch of songs and embed it if you need something working right now.
--
Brian Johnson
Founder and Lead Developer - Jamroom
https://www.jamroom.net