#1 - Dec. 16, 2015, 11:01 a.m.
Blizzard Post
During the weekly maintenance earlier today, we deployed a hotfix that changes the way players receive credit for completing Guild Challenges in dungeons. Challenge credit will now only be awarded for completing a current-expansion (i.e. Warlords of Draenor) dungeon while in a guild group.

To offset this new restriction, Challenge credit will now be awarded regardless of whether or not the Dungeon Finder was used to queue for the dungeon. This means that you can now gain Guild Challenge credit by completing a Mythic dungeon in a guild group! As an additional benefit, we are also increasing the gold awarded by Guild Challenges of all types, by roughly 50%.