Round Robin Load Balancing

The persistence record may have timed out. Looking at the stats you're always going to get the symptoms you describe because there's only one DST add ie the virtual server address. You would normally have DST add persistence with a wildcard vs where the DST could be different. I suggest you remove the persistence type from dst to source.

Worth noting that persistence checks happen prior to load balancing so if there's a persistence record then the load balancing algorithm isn't referenced.