Exact same problem for me since the attacks began. Debug log doesn't say anything execpt auth servers are offline. Other people's logs look completely different though....
GB Log:
[9:33:27 PM:472]:Gatherbuddy 1.7.2.6 - System information.
[9:33:27 PM:473]

latform: Microsoft Windows NT 6.1.7600.0.
[9:33:27 PM:473]:Gatherbuddy executable: C:\xxxxxxxxxxxxxxxxxxxx
[9:33:27 PM:484]:WoW Process with ID xxxxis free.
[9:33:28 PM:545]:Attached to WoW ProcessId: xxxx.
[9:33:30 PM:346]:Gatherbuddy 1.7.2.6
[9:33:30 PM:348]:Authenticating
[9:33:30 PM:362]:Attempting Authorization
[9:33:33 PM:183]:AttemptAuth: Failed (No avaible auth servers online)
[9:33:35 PM:763]:Gatherbuddy is closing down.
HB Log:
[9:30:08 PM:15] Attached to WoW with ID xxxx
[9:30:08 PM:18] Loading Honorbuddy 1.9.6.1 settings.
[9:30:13 PM:529] Authenticating..
[9:30:17 PM:680] Auth - No avaible servers online.
[9:30:17 PM:683] Authentication failed.