For transactions that affect a LOB column to be replicated, the table that contains the LOB column must be marked for replication and have replication enabled.
If pdb_dflt_column_repl is true (the default), all LOB columns in a table have replication enabled automatically when you mark the table (by invoking pdb_setreptable). If pdb_dflt_column_repl is false, you must enable replication separately for each LOB column before replication can take place.