My version is 1.19.1 and with the configs i added, the core I added and the settings everything works.
My advice,...to troubleshoot...start with a whole new retroarch (1.19.1 or 1.20) install on a new folder.
Put my configs in the cap32 config folder, the 4.2.0 core in the cores folder...
Don't use the cfg arguments in LB, just use the configuration I showed.
That way you can rule out any other settings you might have made in your current Retroarch install. And work up from there.