Reduced Loot Tier.
A+ Rating on a Rare 12* would usually be tier XVI (16).
I’m guessing you have not been a member of the alliance for long (or the below situation), hence the reduced loot tier down to VIII (8).
Update 38 : Rectify Rare Titan deadline description
- Version 38 – Put in place a restriction that you don’t get Full Rare Titan Loot if you recieved Rare Titan Loot within 12 days in a DIFFERENT alliance.