After some time, I was finally able to revisit this, and was able to identify (at least in my opinion) 2 different issues.

Instead of providing details of them here, I will open 2 new posts. and maybe new HDE case.

But in summary:

Issue #1:
RefreshListFromDD should not be called when coming back from a grand-parent lookup in the header.
As part of refresh fo the child-list, Clear of the list-DD is sent, which triggers the issue #2.
more details in this new thread.


Issue #2:
Clearing the detail DDO, is clearing one of the grand-parents incorrectly. There is no valid clear path to reach this parent as part of the clear process, as the clear should have been blocked by a constrained parent. (order header in this case).
This issue is happening regardless how the list server DDO is cleared. or by the user, or if by the refresh that is mentioned on issue #1. or any other clearing method that may take place on the child web-list/web-grid.
Actually, we don't even need a grid/list in the view to observe this. Just a BPO with the DDO structures, and having the proper DDO record states, and send clear to the detail will trigger this.
More details, in this new thread.

Regards