I'm having the exact same problem as #1289 but the suggested fix is not working for me. Changing the resolution from default to native doesn't make a difference. Is this a current bug in SteamOS?
Edit: Figured it out, instead of selecting "Native" I forced the resolution to the one I'm streaming at (1080p) + "Set resolution for internal and external display" (this is important, even if not using external display) and that fixed it.