Hi, @mdingle !
There could be a couple reasons for this. How do you currently have your shipping set up? If you want to offer Free Shipping on all orders, I'd recommend setting up one shipping zone with every country that you want to ship to. In that zone, you would add a $0 shipping rate on all orders above $0. It would look like this. Usually, the reason for this is that the conditions of the cart don't match the conditions of any shipping rate.
When I went through the checkout to test this I was actually prompted with the free shipping rate. So, if you already have this set up it could also be that the location you've added isn't included in your shipping zone.
Hope to hear from you soon so we can continue troubleshooting this together!
It could be that I needed to SAVE changes I was making at the completion of each step while setting up Shipping. Yes, I had this problem myself, and I know how it feels. It disappointed me hugely, i.e. I have not been able to rightly set up the most crucial stage in the process – the checkout, the payment. What my customers will think of it! So I tried many things, including clearing Chrome cache files. Now let me first explain the set up I was trying to create. I created two Shipping Zones in the GENERAL SHIPPING RATES profile (including all products): ePacket (including all 44 countries with Free shipping), and Rest of World (including all the rest of the counties, with a paid shipping). Once I had the problem of that message popping up at the checkout, and after I had tried many other methods. I thought let us try eliminating shipping zones, just one taken out at one time. When I deleted Rest of World, the first I eliminated, the problem was gone. I created Rest of the World again, and the problem did not come back. Great! What a relief!