Windows Events for Remote Desktop logon failure
Solution 1:
You will get this logon type 3 when you are using NLA (Network Layer Authentication) as the authentication type since it will try and pre-authenticate you prior to giving you RDP access.
You can test this by changing the security layer to RDP Security Layer. Instructions and detailed information on how to do so are found here: Configure Server Authentication and Encryption Levels -- You should then find when typing an invalid username/password combination that it now logs it as logon type 10.