Hello Vincent,
Ideally if your object is locked by your user, clearing cache/cookies should have resolved your issue. Also you have tried using different system!!
Are you getting this lock message or you are just not able to change the Business Role? If it is just the case that you are not able to edit it, check if your ID has rights to change the Business Role.
I will suggest you to try using different Admin User which has rights to change the Business Roles.
Regards,
Chandan