The climate may just not be to the achocha’s liking: the fruits form, so the pollinators are getting to the flowers, but they must drop off shortly after developing. I’ve searched in vain for any fruits bigger than a sunflower seed.
It was an experiment, to be sure, so I’m not heartbroken over this, just mildly puzzled as to the cause. The tiny, baby fruits look perfectly healthy & the plant shows no sign of disease & has only minor pest issues that I can see.
Achocha Setting Fruit