It seems to be an alliance bug. Background: My characters are in "Danish Knuckleheads" (DK) the other players are in "Champ" (ChG) an alliance guild. When one of my chars, even if there are more then one char of DK on the altar. And a ChG char jumps in even in the last second. Always the ChG guild wins the altar. So it seems that a guild which is in alphabetic order closer to letter "A" wins always the Altar.