Hello,
the issue reported here is most likely related to the Smart Lock which seems to not advertise via Bluetooth anymore. (I assume you have a 5th Generation Smart Lock.)
If this happens, a Keypad can’t connect to the Smart Lock anymore. Then a fingerprint or PIN code can’t unlock the door. If the App also can’t connected to the Smart Lock, the Nuki App, can’t show the PIN codes under Keypad settings. This leads to the impression that the codes are gone, but actually they are just not shown in the Nuki App.
We are currently investigating the problem with a new Smart Lock beta 5.8.4. Please sign up for the beta and report back in the beta thread, if you encounter the issue again.
Smart Lock Ultra/Pro/Go Firmware Beta 5.8.x
If you don’t want to join the Smart Lock Beta, please refer to these trouble shooting tipps: https://help.nuki.io/hc/en-001/articles/33424901856657-Troubleshooting-the-Bluetooth-connection