Ubuntu 18.04 login screen tells me my password is wrong

[マスターズ・イアン]

Folks

I have a bit of a conundrum regarding logging in to my Ubuntu 18 directly.

First, my setup:
* Ubuntu 18.04 LTS on Japanese hardware (including keyboard)
* Menus in English
* Japanese input using Mozc

1. When I login over RDP, no problem.
2. When I login from the console, Ubuntu tells me my password is wrong.
3. On my login screen I have 2 choices: 'Ubuntu' and 'Ubuntu Wayland'. Both end in the same wrong password result.
4. My password contains numbers, letters and an exclamation mark. That is all. All of those characters are the same on the English keyboard layout and the Japanese keyboard layout.

I think this problem appeared after I had to install lightdm to solve my blank screen on login problem, but I'm not exactly sure when, as I usually login remotely.

Any ideas why I'm getting the incorrect password message?

Thanks in advance.

ian