I've got the same issue. Have you solved this?
I did solve it. The problem was that unless you define virtual-hosts in app.war/WEB-INF/jboss-web.xml JBoss will make the application available only to the default virtual-server. So you would need the following in app.war/WEB-INF/jboss-web.xml to make the application available for that virutal-server.
I've also solved my problem, which was different. I've deployed one application into default-host to "/" context and the other application into different virtual-host but also to "/" context. It looks like default-host's contexts intefer with other virtual-hosts contexts.
To solve this i've created additional virtual-host (so ended up with three: default-host, host-a, host-b) and i've moved app from default-host to that new virtual-host. I hope this was it.