Offline HTML Files Assigned to LibreOffice 6

I had LibreOffice 6.2.8 without offline help. I then installed Version: (x64) and LibreOffice_6.3.4_Win_x64_helppack_en-GB (downloaded via qtorrent).

Language Of: User interface and Locale setting = Default - English (UK).
Windows 10 Home, 1809 18/02/19 17763.914

In LO Calc F1 opened Windows Help, Help > LibreOffice Help tried to open in Acrobat Reader DC.
Uninstalled helppack and Windows restart. Downloaded a new copy of helppack.msi via direct link. Now F1 tried to open help in LO Writer but it was a blank page with some HTML in right hand pane. Repair changed nothing.

In C:\Program Files\LibreOffice\help\en-GB\text… I found all HTML files assigned to Libreoffice 1.1 …
Reassigned C:\Program Files\LibreOffice\help\en-GB\text\scalc\main0000.html to Chrome HTML which changed the associations of all HTML files in LibreOffice\help\en-GB. Now, offline help works as expected and I can also open these HTML files in LO Writer.

Is this a bug in LibreOffice, Windows or is it only me?

Thanks, Alan

Offline help should open in your default browser or with app which has been set for .html extension - and it seems very special for your system and settings.