When you save a method, any country that has that method selected as the default loses its selection. Steps:
1. Go to Settings | Ecommerce | Internationalization | Countries.
2. Pick a country or create one. Choose a shipping provider as the default for that country.
3. Go to Settings | Ecommerce | Orders | Shipping
4. Open the shipping provider you assigned in step #2
5. Hit Save and close
6. Go back to the country from step #2. The default is now cleared.
The same seems to happen for payments.
Imar