Unable To Trade

So I got a daily objective today to give 24 emeralds to someone under level 10.
So I went to ragni to try to trade with someone... but when i tried the normal shift + right click, nothing happened.
So i then tried to just type /trade <their username> but that came up with "Can't find that player! Try again?"
But it did that with every single person I tried to trade with, even tho I was typing their names Exactly with capitals and everything.
Is this a bug or did something change that I Didnt see?

 

Hey!
Did these players have ‘[WC X]’ beside their username?
If they did, they’re on a different world and you can’t trade with them.

 

Some of them had just [WC] next to their name, but it still happened with everyone I tried it with and most people didnt have anything next to their name

Is there a way to disable being able to see people from other worlds?

 

/toggle playerghosts or /toggle ghostplayers, I don't remember which offhand but I do know it's one of those.