Inserts waiting on gc buffer busy on Node2. Waiting for Undo block of Node1

I am deleting from a table "TABLEA" from node1. At the same time also inserting records in same table from Node2. Session on Node2 are waiting on "gc buffer busy" wait. P1 value points to Undo of Node1. TABLEA is a huge table and delete takes long time. Its not a partitioned table but has about 28 million records. delete operation will delete about 200K records.I am committing at the end of delete operation. Any idea why my inserts are waiting on Undo block of Node1 ? moreover all sessions waits on same block. All sessions points to same undo file and same undo block. what can be done in this case to resolve the problem? Any help appreciated       

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