ESB SOAPProxy Action with Load Balancer

Issue

We are attempting to use SOAPProxy on an endpoint which points to an F5 load balancer. The endpoint resolves to a Web service which is running on 2 hosts.

Everything works fine when SOA-P and the Web service are running on both servers. However when the Web service is shutdown on one server, calls to one of the SOA-P instances are successful, but calls to the other instance fail when attempting to call the proxied web service with this these messages in the logs:
~~~
INFO [org.apache.cxf.service.factory.ReflectionServiceFactoryBean] (pool-34-thread-1) Creating Service {http://com.example/ist/int/ESBService/v1-3}ESBService from WSDL: http://test-esb01.example.com:8080/identity-service-proxy-1.0/http/ESB?wsdl

ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/web-service-proxy-1.0].[Http]] (http-192.168.1.112-8080-5) Servlet.service() for servlet Http threw exception