SSH can used cached credentials, where it will not prompt you for username/password during the login process. I don't believe I've ever seen NCM use that, but I wasn't really looking for it either.
How do you have your credentials set in "Edit Node"? I find if you can use "SSH2" for "Execute Scripts Using", "Request Configs Using" and "Transfer Configs Using" it tends to work the best.
What "Device Template" is being used here also?