I was at a hotel which used Mifare Ultralight 11 cards. When I used the detect reader option the Flipper crashed. I haven’t seen that with other readers until now.
it isn’t for mifare ultralight. detect reader is for mfkey which is for mifare classic.
I have to correct myself. When you read the card you then have the option to unlock with the reader. It asks you to tap the reader to get the key and it fails at that moment and crashes.