Hi Ranjit
Is it definitely Org assignment and not single role belonging to composite?
If not, is position-based security (PBS) meant to be active in your system? Have you checked if PFUD has been scheduled for this scenario? Is this system part of CUA model?
If PBS is in scope, Have you tracked the user id back (0105) mapping to check for all OSP relationships where access may be inherited from?
if asking about a bug/note it might be worth mentioning which Basis Level and SP you are on?
Regards
Colleen