Difference between with bugs between in actual server and test client.

my mod bugs out and sometimes doesn't work while in a server with my friends, but is perfectly fine in a test world: is there any way to rectify that? like a change to the code or smth I'm playing with other mods but i don't see why any of them would mess with mine to be more specific
when I enchant something with a special block in the test world: it keeps the enchant when removed from the gui, but in the real game the enchant is removed. also a number on the gui bugs out (switching between its base value and whatever added cost from the enchant) in game but not in the test world. The procedures in question follow: 
on gui tick 

on button clicked