When running lp editor users in the console, I get an error:
[LP] You do not have permission to use this command!

But lp editor or lp editor groups work fine.

Spigot 1.12.2-R0.1-SNAPSHOT
LuckPerms v4.2.17

I can reproduce and confirm that error.

Message is being sent because no users are connected to the server - not a permission checking error, just sending the wrong message. :)