I was excited for the Sega CD audio support in the latest genplus core, so I updated, but then discovered this upon loading a game:
This occurs across all games, across all Sega systems using this core. What happened? Is this just a known issue waiting for a fix?
There was a change recently in the way RetroArch expects color data to come from libretro flavors. I would guess this one just hasn’t been updated to reflect the change yet.
Make sure to update to 0.9.8-beta1 (or later) first. Are you using external D3D9 driver by any chance? If so, those broken colors are expected, and you should use the built-in D3D9 driver. Just delete the external one. It’s useless now. Genplus works fine here, btw.
That was the issue. Upgrading to the latest RetroArch solved it, thanks. 
