Graphics issues on PSP GO with Game & Watch (Handheld Electronic) core

I’m getting strange skewed graphics in Game & Watch (.mgw files) when running the latest stable Retroarch 1.8.9 and Handheld Electronic (GW) core 1.6.3. The games seem to run, I can hear audio and input works but the graphics are skewed (see I’m running this on a PSP GO running cfw 6.61.