Blue Post
Original thread hosted on Blizzard's official forums.
The Grand Magister's Key-Cipher mob has a tag limit
View on Blizzard forums:
https://us.forums.blizzard.com/en/wow/t/the-grand-magisters-key-cipher-mob-has-a-tag-limit/2316567/8
Thanks for the reports! There is a fix on the way for the Grand Magister tagging issue.