This generally happens when app permissions have not been granted. We request you to go to your phone's settings, search for "Nymble" (if you are using iOS), and see if the 'Allow Nymble to Access’ section has the toggle for the camera switched ON.

If you are using Android, go to Settings > Search for "Permissions" > under App Permissions/similar, choose Nymble and see if the Camera permission is toggled ON.

Once this is done, please kill and restart the app, and you should be good!