That's not a bug but the standard message due to you joining a guild while there is an ongoing GBG ( joining a guild in the midst of a current season makes you ineligible ), all GBG seasons start on a Thursday and finish on the Monday 11 days later, the current season ends at 08:00 am (Server time ) tomorrow and will restart at 08:00am ( server time ) next Thursday, your announcement will change to one with a countdown timer after the current seasons ends, as you will then become eligible for inclusion in GBG