Before Tuesday maintenance we ran all heroic dungeons as a guild group to get the achievement GUILD CATACLYSM DUNGEON HERO. However, the blackrock caverns part remained grey even after earning the achievement (it shows the players who earnt the achievement though)
I checked forums and noticed issues with other achievements and decided to try again after maintenance. Tonight, we ran blackrock caverns again as a guild group thinking maybe we just need to do it again, but it still is greyed out and wont award the guild cataclysm dungeon hero achievement.
I dont know why it wont award the achievement but its shows that the guild has earnt the blackrock caverns achievement.