Same problem here, really gets annoying by now ... the Mac is restarting almost every night when I forget to close the simulator, and sometimes during the day too

I do have the same problem (and judging by checking on a lot of other apps, they all do ...). The problem seems to lie in a field having isSecureTextEntry set to true - if it is false and it contains some text when selecting a credential from the keyboard, it works - if it is true, then it does not. Also, if you do not select one of the suggested credentials from the keyboard, but choose Passwords, and then select one from the keychain, it does work in all cases. This definitely looks like an issue in the iOS framework.