The error scenario was saving an observation tree(depth > 2) with change in parent as well as a new observation added leaf level at depth > 1. Please refer to the below image for understanding further details.
D, E are new observations added at different levels in existing Obs Tree. A,B,C existing obs also edited. On save of this Edited Obs tree, the result expected in ols A,B,C Obs should be voided. And there will be new A, B,C,D,E Obs. But with the issue in save, the output is getting D observation voided.