Attempting to use the new "score" function in the /tellraw command:

/tellraw @p {text:"Have ",extra:[{score:{name:"Searge",objective:"reward"}},{text:" diamonds"}]}

If the scoreboard is created in singleplayer and scores are set, they will display properly. However, if you switch to a new multiplayer world that does not have any of the required objectives or scores, and run the above command, you will still see the scores coming from players via the last-loaded singleplayer world.

Attempting to create your own objectives and displaying them using the command above in multiplayer does not work either. If the last-loaded singleplayer world doesn't have the specified objectives, then the output is merely "?".