Why does Mochi say 'this deck is empty' for decks which aren't?

I just recently subscribed to Mochi Cloud after using the free Android version for a month. Sync works great and is very fast, but on both Android and web the UI shows all three of my decks as empty when they're not. Here's an example from the web client:

Each of those decks has cards in it (26, 1, and 5). As far as I can tell, everything else works fine - review, stats, all that.

Is this a bug or is this just some UX idiosyncrasy I don't understand?

Yeah sorry this is just poor wording I think. This used to say something like "No decks inside" or something like that. It means that there are not sub-decks. I will probably change the wording back to how it was before.