AsNoriuanswered grow question 3 years ago If it wasn't pollination, then either heat and humidity or spraying in sun or pH huge imbalance . Only in those situations pistils from white quickly shrinks, get brown or diminish other way ...
Hope you will find the answer.
All the best !
P.s. I don't see Hermie balls or flowers, not even single banana, so I don't know why you decided it went Hermie ...