Mutation or stress/cold response? No peppers from this plant all season did this until now.

I would worry about cross-pollination if I were to save the seeds anyway, but now I'm considering it. Maybe I could grow some seedlings of this plant in pots next year to test whether any plants carry on this trait?

This admittedly wasn't the healthiest plant in my garden this year anyway, all my Buena plants have been pretty tiny and low-producing, but maybe better soil conditions would change that, if I grew more from the seeds of this plant.