Need help with SharedNapkin? Email mat.enrique.galicia@gmail.com and I'll get back to you.
Make sure both phones have Wi-Fi and Bluetooth on and are near each other — SharedNapkin connects directly device-to-device, not over the internet, so it needs one of those two to discover the other person. If you're prompted for a Local Network or Bluetooth permission, allow it; without that permission iOS blocks the connection silently.
Your sketches live only on your device. If you use iCloud backup for your phone, they're included in that backup like any other app's data. SharedNapkin itself has no cloud server.
Recognition runs entirely on-device via Apple's Vision framework — accuracy depends on handwriting clarity, same as any handwriting-to-text feature. You can always edit the recognized text after the fact.
Email a description of what happened (and a screenshot if you can) to mat.enrique.galicia@gmail.com — include your iOS version and the app version (Settings → About).