NBT Text Tag won't sync server-side?

Hi,

I made a tile entity whereby you right click, it opens a GUI. You input text into the GUI and press a Submit button.

Then next time you right click, it will say "This is what is written:" followed by the text inputted into the GUI.

It works perfectly in singleplayer but if I try it on a server, the text after "This is what is written", ie the inputted text, is always blank.

Coding(?): I linked a procedure to the Submit button, it creates a NBT Text Tag called "tagMessage1" and makes it equal to the text box on the GUI. On right click of the block, I [Send message] [Get NBT text tag] "tagMessage1":

code for when right click block: https://prnt.sc/vreqei

code for submit button: https://prnt.sc/vreqxs

singleplayer results: https://prnt.sc/vrerej

server results: https://prnt.sc/vrerv1