Hi,
since recently the Monument Lock no longer handles locks correctly. When a player locks one monument, and another one locks another, it is likely that the 2nd player gets an error saying their team already had locked a monument, and cannot lock another one. However, both players are totally unrelated to each other and not in a team.
Edit 17-Jan-2024
Nevermind, I removed this plugin from my server and replaced with "Monument Owner" which provides similar functionality and a bit more. I liked the "Monument Lock" plugin a lot and would pay for it, if it worked reliably. Thanks for your work, and hoping to see an update soon which puts "Monument Lock" back on the rails.