Working as Designed.
Release : 4.8.1
Component : CA Test Data Manager - TDM Web Portal
As per development, when we sync data between source and target, we empty (truncate) the target before we copy all data to target from source.
All data from source is copied to target.
If there is new data in the source table after the sync then the target table will again be out of sync until the next sync job.
This is how the product is designed.