I have had mine do the same, the green capsules begin to ripen the seed, but then before i can notice them dry out enough for me to pluck them,they seem to disappear, then many weeks later I did notice some tiny seedlings emerging from the ground/soil near the old dried out plants, anywhere from 1/2 inch away to about 6 inches away, I am still waiting to see if they do grow & flower though. I was waiting for the seed casules (green) to harden/dry out and pluck the seeds out myself for saving for the next season, but no luck with it.

I had this problem with several of my flowering plants such as periwinkle and then one evening I was out with my flashlight searching for an extremely loud bullfrog and saw ants carring away the seed heads. That's one possibility. Rio

Hi,
Those sheer little gift bags work great to catch seeds, and if something like ants are carrying them off, it will stop that too.
Remy