RAC & Failsafe :: Inserting Large Data Locks The Destination Table In RAC

Scenario:

Our application is using a two instance, one for the live active data and the other for the reports data. We have a process which moves the data from the live instance to reports instance every night. In a single db environment the process is working without any issues. However when we move to the RAC environment the reports db's (insert) in large table get locked and we are unable to insert data to the reports db.

What we are performing is:

Insert into my_table_rpt select * from may_table_live@db_link_to_livedb;

Issues:

my_table_rpt get locked

We have found the workaround by disable locking in destination and subsequent to the insert enable locking

ALTER TABLE my_table_rpt DISABLE TABLE LOCK;

Insert the data to the reports database table

Then

ALTER TABLE my_table_rpt ENABLE TABLE LOCK

Question:

Why does the large destination table (my_table_rpt) get locked in the RAC environment?