Compare job failed due to ORA-14766 (4315702)

Below message is generated in event_log.

Compare job failed due to ORA-14766: Unable to obtain a stable metadata snapshot.ORA-06512: at "SYS.DBMS_LOB", line 1084.ORA-06512: at line 1.ORA-06512: at "SPLEX2603.SP_DEQ_PKG", line 280. [sp_desvr] [module deq]

Compare server log shows that ORA-14766 happened on DEQ_PKG.R_BLOB("PIPELINE").

desvr    2016-07-05 02:05:09.418713 16519 3228591872 [1] running sql statement : (de_select_prepare_to_fetch,L1375)
desvr    2016-07-05 02:05:09.418764 16519 3228591872 [1]   SELECT /*+ PARALLEL (A,2) */ ROWID,ORA_HASH("SPLEX_UNIQUE_KEY"), ORA_HASH("ROOTCONTEXTID"||'~'||"PARENTCONTEXTID"||'~'||"CONTEXTID"||'~'||"AUDITTIMESTAMP"||'~'||"INSERTTIMESTAMP"||'~'||"SERVERID"||'~
desvr    2016-07-05 02:05:09.418764 16519 3228591872 [1] '||"MSGID"||'~'||"INSTANCEID"||'~'||"INSTANCEITERATION"||'~'||"STEPID"||'~'||"STEPITERATION"||'~'||"STATUS"||'~'||"SYSTEM"||'~'||"SUBPROCESSKEY"||'~'||"USERNAME"||'~'||"ROLENAME"||'~'||SPLEX2603.SP_
desvr    2016-07-05 02:05:09.418764 16519 3228591872 [1] DEQ_PKG.R_BLOB("PIPELINE")||'~'||"PIPELINEFLAG"||'~'||"ATRESTTIMESTAMP") FROM "WM02_PRT"."STEP" PARTITION("SYS_P25530") A ORDER BY 2, 3
desvr    2016-07-05 02:22:04.350379 16519 3228591872 [1] Oracle Error 14766: ORA-14766: Unable to obtain a stable metadata snapshot
desvr    2016-07-05 02:22:04.350379 16519 3228591872 [1] ORA-06512: at "SYS.DBMS_LOB", line 1084
desvr    2016-07-05 02:22:04.350379 16519 3228591872 [1] ORA-06512: at line 1
desvr    2016-07-05 02:22:04.350379 16519 3228591872 [1] ORA-06512: at "SPLEX2603.SP_DEQ_PKG", line 280

There was no explicit DDL operation on the table.