Flexible shipping plugin: “There are no shipping methods available”

Good evening community, I’m sorry to bother you guys. I’ve been trying to solve a problem with a store that I’m building for about 6 hours. The problem is that when I fill the billing information I get the legend “There are no shipping method options available. Please make sure you have entered your address correctly, or contact us if you need help.”

The only plugin that I use and that is associated with shipments is “Flexible Shipping”, because it allows me to set different shipping costs depending on the amount of the purchase. If I disable it and I choose “flat rate”, everything is okay. I disabled geolocation just in case, and activated the WordPress debugger but nothing appears. I deleted the shipping zones I had created and left the default one (“Locations not covered by your other zones”) to see if it helps, but nothing.

The truth is that I’m frustrated because I don’t know what else to do, all the plugins are up to date. I disabled the ones that could be causing problems, but nothing changes. I would appreciate any advice or suggestions. Thank you all in advance!

The page I need help with: [log in to see the link]