SharePoint Onine - Search query filter people by AD OU??

Hi we are creating a people search/direction for the organization and would like to to use the search query to ONLY show specific people from a certain OU/group. I have gone down the road of managed search properties e.g mapping a refinablestring111 --> people:memberof. I then queried by typing this refinablestring111:SP-CouncilStaff (SP-CouncilStaff is the OU) however this doesn't return anything?

is this even possible?

Thanks