For some reason its one of those things that works one way as a server action, and a different way as a solo action
I would bug report it but I dont think the devs ever meant for it to be used this way (I have a bad habit of doing that)
Run dom3 in local host mode, with another dom3 open for playing, and it might work.
Otherwise you might just be stuck playing it on my server for as long as the devs allow it to work.