OK I fixed mine after spending all night searching. Somehow in my settings in LaunchBox, when I went to Edit Emulators for Retroarch, this box was checked. I unchecked the box and all the games started launching again. Here are some articles I read through and eventually tried this suggestion. Hope they help someone else.
I am running into a similar problem. Upgraded to 11.9 and been away for few weeks and now none of my games will launch in Big Box or LaunchBox using Retroarch emulator. Was working fine before. Is there some setting I have to update or change? Games work fine if I just use Retroarch. Very frustrating.