When I remember correctly does /lp group default listmembers not show all members in that group (Because of code or whatever).
If that's still true should there be a note/message about this when using this exact command, to inform tha player about this fact and reduce confusion about why some players aren't displayed within that group's listed members.

And I think that is should show at least online players (that are in default).

Yeah this confuses so many people.