Ubuntu datetime locale on login screen

I've installed Ubuntu 19.10, language/locale/formats are set in US/en. And everything seems to work OK, except datetime language on login screen (when I turn on my laptop and see fields for user/password logging). It has local-language-style. So, datetime language for user / lockscreen picks up correctly, but for login screen - nope. What's the reason and how can I fix this ?

Output of locale command:

LANG=en_US.UTF-8
LANGUAGE=
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC=en_US.UTF-8
LC_TIME=en_US.UTF-8
LC_COLLATE="en_US.UTF-8"
LC_MONETARY=en_US.UTF-8
LC_MESSAGES="en_US.UTF-8"
LC_PAPER=en_US.UTF-8
LC_NAME=en_US.UTF-8
LC_ADDRESS=en_US.UTF-8
LC_TELEPHONE=en_US.UTF-8
LC_MEASUREMENT=en_US.UTF-8
LC_IDENTIFICATION=en_US.UTF-8
LC_ALL=

Solution 1:

Just go to System Settings -> Region & Languages -> Manage Installed Languages.

Then you can choose your things and then select Apply System Wide..

Read the text under "Apply System-Wide" Tab. Which is

Use the same language choices for startup and the login screen. when you are in "Language" Section.

and

Use the same format choice for startup and the login screen. when you are in "Regional Formats" Section.