The default settings in the MW OSD on my configuration resulted in the artificial horizon on the roll axis being reversed.
Edit two settings in the MW OSD firmware.
In config.h, uncomment "REVERSEAHI" as below;
#define REVERSEAHI // Reverse pitch / roll direction of AHI - for DJI / Eastern bloc OSD users
In screen.ino, I used these settings;
#if defined REVERSEAHI