Here are the basics. Password reset never worked on my system. I finally got motivated and got it going a five years or so into it. The short story is there were numerous things causing it all together. One was the cron didn't see to be running.
Upon getting that working, and setting the delete old users to 3650 days (ten years), then turning off that feature in the cron scheduler I have anywhere from 1-2 user accounts just plan disappear every day. They are relatively new user accounts as well (within the last year). I can't see anything that looks like it would do this in the settings? Any suggestions?