I checked at the subscriber (REP-DB). When I click "View synchronization status" at the subscription, it shows "Synchronization in progress".

I also checked one table where the data is continuously growing.

At publisher (MAIN-DB), the table has 23082538 rows. The count increases by about 20-30 every minute.

At subscriber (REP-DB), the table has 23007930 rows. The count stays unchanged for several minutes, then suddenly increased to 23008130.