Shipping by total always shows "calculated during checkout"

Hello, I have two price bands one for sub-£40 purchases and one for +£40 carts.

Under configuration >> shipping >> shipping methods I have one method "standard delivery".

Under configuration >> shipping >> shipping rate computation methods, I only have shipping by total.

The config for this only has the two options above. The box "limit shipping methods to configured ones" is ticked.

Under the general shipping options, none of the boxes are ticked. Specific of note here the "estimate shipping" is not ticked.

For some reason, all carts show "calculated during checkout".

Locations are limited to UK only, all others are unpublished.

What hidden beauty of a tick box am i missing to show the shipping not the message?

Many thanks

(It's been a while since I looked at that, but I believe...)
Most shipping plugins only implement method GetShippingOptions() and don't implement method GetFixedRate() -  Only FixedRateShipping does.
You'd have to customize the 'Shipping by total' plugin.