I have had a group go hermie/seedes from fem seeds also. It sucks, but it was my fault. I think Feminized seeds have a tendency to go this way because of stress.
I had just changed my soil mixture, and was not used to how I needed to water them for the first group, and I stressed them out. Most had some seeds toward the bottom of the plant. I checked my roots after cutting down, and the roots showed signs of stress from under watering. I now have the watering set up to work with this soil medium, and the plants are super happy, and NO SEEDS!
Just do your homework on the conditions that could have stressed your plants, and be mindful of any changes you made to growing from when you had a good crop and a bad crop. Good luck!