Access Policy update difficulty

I have made 5 or 6 sites with Modx Revolution in the past and not had any problem updating Access Policies. Now, I am using MODX Revo 2.2.1-pl (traditional). I can duplicate an Access Policy but then I can't update it. I change the details of the duplicated policy, click save. Things look fine. But when I go to use the updated policy I see that it hasn't been updated at all (still has the default name, which I had changed before saving, and the default number of permissions).

I have two sites using the same version of Revo on the same server (Apache/Linux/PHP5.3) and have exactly the same issue with both. Is it just me or is there a bug here?