Unable to intercept some groupchat packets

I am running Openfire 3.3.2 on machine A which also has a spark client X. There is another Spark client Y on machine B . Both X and Y are registered as users of the Openfire on A. We have a plugin that implements the InterceptPacket interface of Openfire and intercepts all packets. When X and Y are in a chat, we see that all chat packets as well as IQ and presence are being intercepted.

When X starts a group chat from its menu and invites Y and Y accepts invitation , we see that presence and IQ packets are being intercepted. Lets say the groupchat name is X_abc. Subsequently, when X types data in its groupchat window, it shows up in Y’s groupchat window. But we do not see any intercepted packet from X_abc to Y. We see packets from X to X_abc. Similarly, if Y types data in its groupchat window, it also shows up correctly in X’s groupchat window. But again, we see data from X_abc to X but not from Y to X_abc.

Is it a bug in Openfire 3.3.2 ? Has it been fixed in a later version? Or are we doing something wrong ?