It's possible that something was missed when initially setting up, @HLG!

When setting your delivery fees up to be distance-based, there are a couple of things you'll want to look at. First, you'll want to make sure that you have entered fees into each row underneath the Fees column. Next, look at the column titled Free for orders over, and take note of the checkboxes next to the $ amount spaces.

If you'd like to waive the distance-based fee for orders over a certain amount, check the box on that row. If you have boxes checked in this column, delivery will be free for orders over the amount notated in the $ amount space. 

The last thing I'd recommend taking a look at is the Fallback delivery fee section just below the Delivery fee section. If a customer places an order, and their distance is greater than the distances you've set fees for, adding an amount here will ensure that those customers will still be charged a delivery fee.