Shipping methods doesn’t work

I’ve created a simple coupon offer where it’s 10% off when the customer spends over ￡45.

I want it selected for a particular shipping method which the plugin claims to do. The shipping method is min ￡40 spend which is fine as 10% off ￡45 is ￡40.50 – over the min needed.

However, all I get is “Sorry, this coupon is not applicable to selected shipping method” except when I take all shipping methods off which isn’t helpful…