QuickPress/inserting media

I seem to be having problems inserting any sort of media via QuickPress. I’m running a production and dev site with the same plugins and WP version, and have tried turning off all plugins and changing the active theme on the dev site with no luck. I checked file permissions and didn’t find anything weird.

When inserting say… an image, the Add Media window comes up and acts normally, but when I Insert into Post nothing happens. Nothing is inserted at all. All functionality works as expected in full editor mode. Ideas?