On the backend, the Tier Price is well configured.
On the Frontend, it's OK I can see it when I'm logged in as a customer belonging to the right group.
When I add a product to the cart, the tier price applies correctly.
But in order processing this tier price was remove (it's basic price whose apply in order).
After that, the same issue appearing in cart and for other product who have tier price configured, I need to logout / login to have good price in cart, but still impossible to order at the right price ...
Have you got an idea to fix this bug ? Is exist a patch to fix it ?