I know this has been an issue for a while but didn't know if it had been reported officially? I know others have experienced this. But the issue is that when you are in an Intellivision profile mode. There are some menu screens that when navigated will extend to the far right side of the screen. But when you back out of those menu screens. Then characters will remain stuck on that far right hand side. And even if you exit all the way back out of the menus and back to using the RGB2HDMI, they remain.
Only way to remove this is a to do a reset on the RGB2HDMI or power cycle it.