install built-in help

users
#1

Good evening
(Windows 10, LibreOffice 6.0.4.2, Japanese OS, selected interface language: US English)
When I press F1, I get the error message:
"LibreOffice built-in help is not installed on your computer."

I downloaded both the English AND the Japanese versions of the built-in help file and stalled both.
Regardless of the interface language I choose, I still get the above error.

Is there a trick to achieve this.
Googling showed answers like selecting the appropriate IF language, but that apparently does NOT work.

Thank you
Thomas