Trying to make sense of the AWR report

I want to know how to interpret the AWR report result.

Segments by DB Blocks Changes           DB/Inst: HEVQC/hevqc  Snaps: 8639-8640
-> % of Capture shows % of DB Block Changes for each top segment compared
-> with total DB Block Changes for all segments captured by the Snapshot

           Tablespace                      Subobject  Obj.      DB Block    % of
Owner         Name    Object Name            Name     Type       Changes Capture
---------- ---------- -------------------- ---------- ----- ------------ -------
SYS        SYSAUX     WRH$_SYSMETRIC_HISTO            TABLE       29,440   32.45
SYS        SYSAUX     WRH$_SYSMETRIC_HISTO            INDEX       28,896   31.85
** MISSING TEMP_I     ** TRANSIENT: 421068 MISSING ** UNDEF        4,352    4.80
SYS        SYSAUX     WRH$_SYSMETRIC_SUMMA            TABLE        3,920    4.32
SYS        SYSAUX     WRH$_SYSMETRIC_SUMMA            INDEX        3,824    4.22

What is the missing temp_i in the middle means? The tempfile is still there in the directory.