I could be wrong - but somewhat recently - when leading a raid and group one was full, I used to be able to invite people to the other three groups by continuing to type /i NAME. As long as the other groups were formed, but not full, it would just add the person into the next open slot in the raid. This was a nice added feature.
Lately, when group one is full, if I use /i NAME - I get the old "your group is full" message and I have to have the individual group leaders invite to groups 2 3 and 4.
Anyone else experiencing this?