Android - Fingerprint scanner stops working after 5 attempts?

Question

A bit of a weird issue when using the fingerprint scanner in Android 6.0 (Marshmallow) that I am stuck with and can't figure out.

I have searched all over but can only see things related to hardware defects.

The application accepts, encrypts, decrypts and validates fingerprints just fine, however it only allows 5 attempts before it for some reason stops working. (More on that below)

I have setup the application to allow the user four scan attempts before implementing a security lockout timer, however if I intentionally fail to authenticate 4 times. Then I wait to lockout period of 5 minutes and come back I can only scan my finger once, after that the fingerprint appears to stop listening until I force quit the application from Applications Manager?

It then accepts fingerprints again.

Code for authenticationFailed callback:

@Override
public void onAuthenticationFailed() {
    authenticationDialog.dismiss();
    cancellationSignal.cancel();

    //Add one to the number of attempts taken
    attemptCount += 1;

    if (attemptCount < maxAttempAllowance) {
        AlertDialog.Builder message = new AlertDialog.Builder(appContext);
        message.setTitle("Authentication Failed");
        message.setMessage("The finger you scanned is not registered in your devices settings or your device failed to identify you.");
        message.setPositiveButton("Try Again", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                dialog.dismiss();
                showAuthenticationDialog();
                startAuth(manager, cryptoObject);
            }
        });
        message.setIcon(R.drawable.cross_flat);
        message.setCancelable(false);
        message.show();
    }
    else {
        AlertDialog.Builder message = new AlertDialog.Builder(appContext);
        message.setTitle("Authentication Failed");
        message.setMessage("You have exceeded the maximum login attempts allowed. Try again in 5 minutes.");
        message.setIcon(R.drawable.cross_flat);
        message.setCancelable(false);
        message.show();
        setSecurityBanTimer();
    }
}

Even without the lockout security code the scanner still only accepts 5 prints.

Answer 1

I have found at that the API forces the security to have a 30 second gap between 5th and further attempts.

This means that the scanner will be unresponsive after the 5th attempt if the security of the application sets lockout at 4.

Documentation:

Device implementations with a secure lock screen SHOULD include a fingerprint sensor. If a device implementation includes a fingerprint sensor and has a corresponding API for third-party developers, it: MUST rate limit attempts for at least 30 seconds after 5 false trials for fingerprint verification.

Find information here.