**missing** owner in the segments by db block changes for temp tablespace

I am getting an entry for the segment by db block changes with the following values in the AWR report:
Owner: **MISSING**
tablespace name: TEMP_TBLSPC
object_name: ** TRANSIENT: 25691776
subobject_name: ** MISSING **
object_type: UNDEFINED
db_block_changes : 3,408,304
%captured: 6.68.

I am not able to understand what does the object_name: ** TRANSIENT: 25691776 exactly means and why is the object_type undefined .

Any suggesting regarding the same is appreciated.

Regards,
Rohan