Well, the solution is SetClientViewEntity then set third-person view on the client.
Since SetClientViewEntity will cause the client ViewModel invisible, setting third-person view on the client makes ViewModel visible again.
It works on tf2 by this method. See:
https://github.com/tf2-sandbox-studi...urityCamera.sp
I had also tried changing the m_iObserverMode, it works but not the best.
Maybe you can try setting the client third-person view after SetClientViewEntity on other source game.