Is rebooting to a new software installed on a partition the same as running touch /service/mcpd/forceload and reboot?

Well, as per the current setup, it should always send to PG10 member.

Can you try the below once and see it outcomes.

Your loadbalancing method is on the node, the Member vs Node do play a major role in load balancing decision and there have been previous bugs where a single member gets selected alone and serves for traffic (ignoring other pool members in the cluster).

When you put least-connections-member its totally w.r.t to the existing pool. least-connections-node is throughout the box. To avoid confusion, you can just revert if to default RR load balancing.

Also by any chance you have persistence in the VS.