This bug is repeatable - so much so that I took a video of it. I’ll provide whatever I can to help fix it. This is the latest stable version. The video is here: https://onedrive.live.com/redir?resid=7c40e6c8524f7a0c!336172&authkey=!AExkHWB8M2v4Q48&ithint=video%2cmp4.
The process is pretty straightforward. Start with a single node, highlight it, expand it and then click anywhere on the diagram. It does not occur if you expand it first. I do have an event that listens for the LayoutComplete (which seems to fire for every node added, not when all nodes are added - I guess I should move this to a transaction) but any, it always happens.
Jeff