Refine and Review phase

I think I’m missing something. Can you help?

During a change process my affected objects are set to Under Review with a Pending Change icon (red triangle).

At that state, no one can edit the object.

During the rework/clarify loops I use the Refine phase and Review phase of the LifeCycle to move the state during that phase.

At the moment I am moving the object to “In Work” at Refine but the problem is that now the objects are open for users to modify not just the assignee of the task. I see there is a Roles and Access Control tab for the Under Review phase that looks like you can grant Ad Hoc access to those roles (Assignee and Reviewer).

But when I have Refine stay at Under Review, the Assignee can’t edit the objects even with the ‘special powers’…

What am I missing? Do I need another State that is used just for Refine to move into and then a policy that locks edits in that state.