OneDrive for Business is showing I've used 700BG of space even though I've deleted everything.

OneDrive for Business is showing I've used 700BG of space. However, I have deleted everything from OneDrive and emptied both levels of recycle bin. 

Even the OneDrive page that shows you the biggest files in OneDrive is empty.

And yet OneDrive claims 700GB are in use.

 

I have NO files. Why is OneDrive showing 700GB used space?