RGB output with sync from composite + sync stripper is janky

Oh, alright. Don't worry too much about the shield. It means ground as well.

Well, now I'm out of ideas. It's good that your setup works with Mega Drive on Composite and csync..

 

In case anyone was looking for resolution on this: I bought a new cable and it fixes the problem. It also fixes a problem I was having with my SNES before where there were these annoying white dots that would crawl up the screen, which I was told was just my system being kinda borked, so I guess that cable was kinda fucked to begin with. Pretty happy that that was not the case. Now everything looks absolutely amazing, like I was trying to get it before.

Thanks so much for the help anyway, I learned a lot from this thread. You guys are great, really.