A cursor scan of an unpartitioned heap table can read all data up to and including the final insertion made to that table, even if insertions took place after the cursor scan started.
If a heap table is partitioned, data can be inserted into one of the many page chains. The physical insertion point may be before or after the current position of a cursor scan. This means that a cursor scan against a partitioned table is not guaranteed to scan the final insertions made to that table.
If your cursor operations require all inserts to be made at the end of a single page chain, do not partition the table used in the cursor scan.