I think this is almost the issue as Bug #479553 (Moving shape with connectors, connectors go wild).
The vertical line as a connector attribute (inkscape:connector-type) but no start and no end connection. That's probably the reason why it jumps to unexpected places.
I think this is almost the issue as Bug #479553 (Moving shape with connectors, connectors go wild). connector- type) but no start and no end connection. That's probably the reason why it jumps to unexpected places.
The vertical line as a connector attribute (inkscape: