When logging in today, I saw a notification that there were 31 suggested edits to be reviewed (which is an unusually large number), but when going to the review page, the queue was empty.
Even after refresh, the indicator remained in the top bar.
They're not suggested edits...
That's everything waiting in all of the queues. As a member of the site with moderator privileges, you're trusted with information on what's happening outside of your specific area, now including the total /review backlog.
Normally, it should turn over fairly regularly: if you notice that's taking a long time, try to drum up some enthusiasm for the task from your peers - otherwise, the reviews you've done that are blocked by the need for others are just wasted effort.