Only seems to affect the current leader of the group.
${Group.Member[1].Name} is not reporting the first party member, its reporting the group leader, so when you work your way to ${Group.Member[5]Name} rather than getting the last party member you get the fourth party member.
Subsequent to this, ${Group.Member[Party5]} will return Null if you are the group leader. It only works up to Party4.
So near as I can tell this only affects the current group leader, everyone else reports properly.
