This sounds like the Sage client is launching and closing. Have they tried removing the published app altogether, and trying to republish, and re-checking the argument line to make sure there is no typo there? (though come to think of it, if there is a typo, Sage would still open, with the empty white screen). Just something worth trying. It does sound like something that is specifically with the Sage published app if it all works outside of that app. One other thing to try, what happens if you login with the user trying to launch the remote app through actual RDP session, and launch Sage, using the same exact parameters set in the published app.