Since failed IATs must be overridden by the credit union, there is a Tracker record along with a corresponding Tracker conversation for each failed IAT.  To view these IAT override Trackers, refer to the AT Tracker on the base share (000) account for the member.  For further research use Tool #664 Print Member Trackers to view all OFAC overrides.  In the report filters, enter AT Tracker Type and OO (override OFAC) Memo Type.
Additionally, the PACXTB4 report shows all IATs, including the failed IATs.