Command block text replaced with ######

Hi, I am writing to report a bug *that I am experiencing. I am using the "/fill*" command via command blocks (mainly chain and repeat) and once i put in my data and exit the tab it replaces my data for "#" on every "space" and every "letter/number". This is the first time it has happened, at first i thought it was because of the distance of the command: In my case the command was "/fill 1139 80 1248 1139 4 1384 border_block 0 replace air" however i did an command the same distance and height but it worked briefly until "#" was replaced for my code.

Hopefully you see this and can give a solution. Thanks