There is a possibility for situation in which you can enable a incremental view, but cannot refresh it due to wrong order of tables being joined and 'unknown column' exception.
I resolved the situation by editing delta.sql file on line 655, originally it ordered the tables by idx, i changed it to mview_join_order ASC, mview_table_id ASC, idx;.
My problem was solved by this, can you confirm if this is a bug.