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=