Blizzard have announced that players can now claim their Keystone Master reward and given a timeframe for when those that already claimed it will receive the reward.
Keystone Master (Source)
It should be safe to earn the achievement now and collect your reward. Anyone who’s earned the achievement prior to this fix will earn their reward early next week.
And the original post:
KSM (Source)
In order to address a bug, we have disabled a part of Keystone Master.
At this time, players will not get the Draconic Mark of Mastery from completing Keystone Master. Once we re-enable it, the fix will be retroactive.
Thank you for your patience and understanding.
