LOB data is blank (4231301)

The size of BLOB column in target shows zero, and it looks the data is not posted or truncated. Especially in case the row having the size of above 4k, this issue happens.

-- Source

select dbms_lob.getlength(MRP_PHOTO_IMG)  from TABLE;

DBMS_LOB.GETLENGTH(MRP_PHOTO_IMG)
----------------------------------------------------------------
38461

-- target

select dbms_lob.getlength(MRP_PHOTO_IMG)  from TABLE;  

DBMS_LOB.GETLENGTH(MRP_PHOTO_IMG)
----------------------------------------------------------------
0

Oracle doesn't write redo entries for LOB data with the size of above 4K and NOLOGGING attribute.

According to storage attribute for LOGGING, it acts differently as following.
LOGGING: enables logging of LOB data changes to the redo logs.  
NOLOGGING: changes to LOB data (stored in LOBSEGMENTs) are not logged into the redo logs, however in-line LOB changes are still logged as normal.

The row data above 4K is treated as out of LOB in Oracle.

Change NOLOGGING attribute to LOGGING for LOB column.

For example:

ALTER TABLE table_name MODIFY LOB (lob_column) (LOGGING);