Delete Org membership API doesn't work

I'm trying to call the DELETE API on the endpoint /ApiServer/portal/roles/config/membership/Org/{UID_Org}/{UID_Person} and I receive a 200 OK response with the membership details, but the membership is not removed. Is it an API problem? Has anyone encountered this problem? Any suggestions on how to avoid this and remove a membership?

Thanks in advance,

Fabio