No cards due today, new card are due

Hello.
I have used both Anki desktop (Mac) and the iPhone App for 5+ years, and I sync them every day through Ankiweb. I have over 20,000 cards, with over 500 cards due each day.

Today, I have no cards due either on the desktop version of the iPhone app. They show the same status.

Any ideas for how I should go about fixing this?

Thanks.

A day has elapsed, do you have cards due again now? Have there been any recent timezone changes? Do you use any add-ons? Have you used the ‘set due date’ feature at all?