Yes, it is.
But I've figured it out :)
What was happening is that when I made the failover gateway group, I also added a firewall rule to route all LAN traffic through this gateway group. Since WAN-1 is healthy, all traffic (as per this rule) is routed to WAN-1. But inserting a new rule whereby I allow traffic to the single host that I want to connect to and only on the protocol that I want to use (http) solved the issue!
Thanks for the rapid fire back and forth, much appreciated!