The topology nodes in the tree are being constantly overwritten by the FlowCapableTopologyExporter. The latter listens to link discovery events and unconditionally puts information about a link into the tree, even when the link was already known, not newly discovered.
It doesn't seem right to update the topology data when there are no real changes, 'cause it may trigger data listeners with some side effects and any custom augmentations of the topology subtree will be lost.