Olympus trip seems to share the same mistakenly built in workaround for manual 200th exposures as the pen series… cover the selenium cell so the red flag pops up and hold the button down while rotating the flash aperture selector all the way to 22… be careful as it will go off if you hold it too had.
then, select your desired aperture and press firmly. voila! 200th sec. selectable aperture… just not that quick to pull off.