LO offline help/F1 for Linux [SOLVED]

I have LO, VCL:gtk3, UI:en-US on a MX Linux 19.4, when I tried to access F1/LO Help, it opened Calibre with the following error Help Page Redirection by Unknown [ZIP] Already in calibre: Help Page Redirection by Unknown [ZIP]

Is this a bug for Linux version or I’m missing something? I’m pretty sure the help file is installed (package manager showed the LO-help-en-US is installed, I’m assuming this is the offline help file that I should install).

ps: the main reason to access help is to check the conditional sections formula syntax, which I couldn’t find in user manual.

LibreOffice uses xdg to invoke the system browser with the help page URL.

Calibre must have been set as default HTML application in your desktop settings. Please verify.

Thanks for this tip, it solved the problem.