This is expected with Data Domain storage. VDP doesn't get an updated replication status until the data domain completes replicating a client backup. More specifically VDP uses data domain managed file replication. VDP doesn't update the progress until the Data Domain completes replicating a file. You can see progress via data domain command "ddboost file-replication show active".
This EMC KB has some more info regarding how it works: https://support.emc.com/kb/464759
By design VDP replication job ends after around 24 hours. If this is the first time running a replication job you might need to let it run for a few days to "seed". The first replication for each client will take significantly longer. After the first it can use synthetic aware replication which uses significantly less bandwidth. If you've been running the replication job for awhile you might need more bandwidth.