Date & Time:
16th July.

Frequency:
Always.

Character Name:
Mir Ain.

Race:
Miqo'te M.

World:
Balmung.

Class/Level:
White Mage 50
Black Mage 50
Summoner/Scholar 50

NPC Name:
Jonathas.

Steps:

In 1.0, get WHM and BLM to 50.
In 2.0, get SMN to 50.
Complete SMN storyline.
Complete SCH storyline.
(re)Complete BLM storyline.
(re)Complete WHM storyline.
Approach Jonathas on WHM.
Receive "no achievements" dialogue.
Check title list.
Find "Archmage" is not there.
Zone.
Approach Jonathas on BLM.
Receive "no achievements" dialogue.
Zone.
Approach Jonathas on SMN.
Receive "no achievements" dialogue.
Zone.
Approach Jonathas on SCH.
Receive "no achievements" dialogue.
Check current achievements.
See "Mastering Magic" is complete (see screenshot.)
Be very confused.

Screenshot of achievement screen for reference:



...Halp.