Hello there
I have installed LuckPerms on my Server. It is a great plugin but unfortunately /gm 1 stopped working. It gives me no response when I type in /gm 1 but when I disable LuckPerms it workes.

Its most likely do to you lacking the permission to run that command. Try verbose to see what permission node is needed and then set it.

https://github.com/lucko/LuckPerms/wiki/Verbose
https://github.com/lucko/LuckPerms/wiki/Usage