DMS task does not transfer data changes from source table to target table

DMS task has been running for 1 week. When I examine the changes after full load, it only transfers the insert operations to the target table. The source table contains data that has changed. Table statistics: 768 insert, 0 updates, 0 delete.

Source: RDS PostgreSQL Target : RDS PostgreSQL Our all source tables have PRIMARY KEY. DMS tasks are running as full load + CDC

What could cause this problem? What configurations should I check? Thanks for your help.