Hi sorry, just saw this. Originally it was a weight and dimensions issue on a particular product. Once that was resolved, everything started to work properly.
Things for you to try if you haven’t already resolved this:
– set up shipping zones, even if its just for your country. Then add the methods inside of that zone.
– make sure you have weights assigned for all products if your courier requires them
– make sure your hosting allows for api’s
– make sure you have the rest api operating
Hope that helps.