What version/build of NametagEdit are you using? Type /ver NametagEdit

4.1.3

What version of Bukkit/Spigot/PaperSpigot are you using? Type /ver

http://prntscr.com/dglprg

What plugins are you using? Type /plugins

http://prntscr.com/dglpxk

Please explain your issue?

Cant use spaces

How do you reproduce the issue?

/nte player xMadz prefix &7&lowner

Is there an error(s) in the console? Please use: https://pastebin.com

No

Put in double-quotes:
/nte player xMadz prefix "&7&lowner "