Something wrong with Magic Attunement talent or UI. For example, Dampen Magic spell shows in the UI the increased 50% effect (180/360) but when cast on the character the buff in the UI shows the basic Dampen Magic effect (120/240). Have not tested whether the talent actually works.
Buff tooltips always show un-talanted numbers. For all buffs of all classes. From tests done by others, the talented numbers actually apply, it’s just a visual ui bug that Blizzard isn’t bothered to fix since launch of Classic.