They had it ready to add then didn't or couldn't and seem to have given up. There are thousands of users left waiting and have no idea what is going on. No explanations have been given.

Either there is a technical issue that takes months to resolve, Duolingo just doesn't consider it a high priority or they have decided that courses without audio now pass as complete.

Staff, for unknown reasons, simply haven't added it yet.

I gave up a long time ago :(

If they aren't providing a sound explanation, I guess they have no excuse. It's pretty lame, imo.