Login to local user account doesn't work after joining Windows 10 machine to Active Directory Domain

The title basically says it all. I also tried adding the local user account to the Power Users Group as referenced in this post here:

Unable to login with Local account (user) after joining onto domain

But in my case, I don't have any special GPOs on my domain that control access for local user accounts. Like the post above, if I remove the computer from the domain, then I can login to the local account. I've also tried changing the password to match the domain password policy in case that was the problem, but the account still can't login. I tried putting the local user in both the Power Users Group and the Administrators group for the local computer, but result still the same. It just gives me the generic "The username or password is incorrect. Please try again." error. The computer in question is running Windows 10 Pro, and the Active Directory server is running Windows 2003 equivalent (SAMBA).

Any idea what could cause such behavior?

P.S. I did try both the COMPUTERNAME\Username and .\Username formats for the login and got the same result.