Found this. If that’s not it:
I don’t have a Steam Link, but my first thought is that OpenGL might be an issue, since most games use DirectX (it’s supposed to compatible, but it might be buggy or something) and because the audio works. You could try having RA use d3d as the video driver, to see if that makes a difference. You have to switch to the RGUI menu driver iirc.
Does this problem only happen when you load a game, or does it apply to the menu as well?
Have you tried connecting your monitor to the Steam Link? Just in case the TV isn’t happy with the signal for some reason.
It might also be streaming the command prompt (or trying to) instead of the normal window. Not so sure about that though. Try DeSmuMe; the post from earlier got a white rectangle instead of a black screen with that core.
Hopefully some of this is helpful.