John, not able to reproduce in SW2016 SP 5.0 and have not seen this behavior in earlier or latest versions. Is this a file specific issue? Can you reproduce it on other files? Could you suggest a workflow o reproduce it (if different than what you've mentioned above) and possible share some dummy files to check?
I have noticed it happen a lot over the past year or more. I therefore don't think it is file-specific.
The workflow I described is exactly what I did to cause it, as far as I know.
I have just got used to it, I suppose, but this morning it irritated me enough to enquire about whether it was intended behaviour.
I'll see what I can do regarding example files.
We are just about to close for the Christmas break, however!
I have SW 2017 SP5.
I opened an assembly, highlighted a component and then expanded it, and my highlight jumped to the top of the tree.
I am not sure if I have ever seen it before. I may have never noticed. But it happened.
However, now I can't reproduce it no matter what I do. It only happened that one time.