So, seems to be a fair few fixes related to this and other UAR issues in SP13
Note 1822778 - Master Note for SAP Access Control 10.0 - Support Pack 13
Implementing now and will report back if my issues are fixed.
Note 1865864 - UAM: Wrong data in UAR Request & adding Expired Roles filter
Note 1866292 - UAR requests showing role usage for deleted roles and users
/henrik