Unable to login after fresh install on Ubuntu 18.04.2

[Fhionyer Perhair]

I'm writing about a bug in Ubuntu 18.04.2 (Server edition). The issue is that, after going through the setup procedure, the given username/password that I enter do not work.

The username and password I've tried are:
user1234
pass1234

I initially thought I was hallucinating, so I repeated the process several times and can confirm it's reliably reproducible.

EXPECTED RESULTS:

1. Load the ISO onto a machine that's not connected to the internet.
2. Go through the installation process, using the username 'user1234' and password 'pass1234'.
3. After installation is successful, login with the details above.

ACTUAL RESULTS:

1. Load the ISO onto a machine that's not connected to the internet.
2. Go through the installation process, using the username 'user1234' and password 'pass1234'.
3. Cannot login with the details above after installation is complete.

OTHER NOTES:

I suspect that it's related to the fact that I was installing Ubuntu (Server edition) on a machine that's not connected to the Internet. An auxiliary observation is that, the installer hangs for over an hour while attempting to download packages. I suspect that there has been a lack of testing done with the installer not connected to the Internet.

I'm not using a custom keyboard or anything like that, just a standard en-US keyboard.

The architecture is x86_64.