Is Are there 12sec clips in the ‘events’ tab, and just no notifications? Person detection is essentially just a filter that prevents the cam from sending you notifications with every motion event. So if you turn it to notify on all motion instead of person event, does it then notify correctly?
Go to one of the cams, hit the gear icon in the upper right corner, and go to ‘event recording’, check that ‘detects motion’ is turned on.
Back out and go to ‘notifications’, check that ‘send notifications’ is on, and ‘all other motion’ is on. ‘person’ will toggle off when you turn ‘all other motion’ on.
Back out again, go to ‘event recording’. In ‘schedule’, either set it to ‘all day’, or make sure you’re not outside the time it’s told to monitor.
That should cover everything that has to be set to have it capture motion clips and notify to your phone.