When a ReplicatedTree is constructed using ReplicatedTree(JChannel channel) a pre connected channel must be used.
This means that the tree which sets itself as the receiver for the channel misses the viewAccepted callback and (when this member is the second member) therefore doesn't set the send_message flag to true.

Subsequent modifications to the tree on this node do not get replicated (or notified to the other node's ReplicatedTreeListener).

Using the ReplicatedTree constructor that creates a channel implicitly is not affected by this issue.