Safe to say it's not E. uniflora.
Are you sure the fruit was ripe? My guess the fruit wanted to get a bit darker in color.
Could be a mutation. Another possibility is it is a hybrid of grumichama and a similar species like E. blastantha, E. ophthalmantha or E. itaguahiensis. Hybrids sometimes have quite different characteristics from both of the parents. I trust you have already asked the seed supplier.