ADD on the ENGAGEMENT RELATED LIST on PLAN Form doesn't behave as expected on Audit WS?

[User664605]

Hi Team,

I am facing an issue in all the environment including PDIs in Zurich version.
Issue - ADD UI Action on Engagement(sn_audit_engagement) Related List on PLAN(sn_audit_advanced_plan) Form doesn't behave as expected. It shows the message "Successfully addedd 1/2/3 items to the list" on selecting Engagements from ADD ui action but doesn't reflect afterwards. Please check the image attached.

Whereas; The same action to add existing Engagements to a PLAN via Native UI "EDIT UI Action" is functionable.  It allows adding existing Engagements of State Scope Validate or Fieldwork to the plan successfully. Please refer the image.

Kindly share the probable cause if any of the experts is aware. If not, is there Any KNOWN Errors or Problems raised to fix as its an OOTB component?

For our CLIENT Use Case; we would like to restrict the ADD/EDIT functionality to be visible only to a specific group. Hence I am trying to understand the possibilities and OOTB behavior.

Thanks in advance.