The name tag doesn't show names over the mobs nor the players' gamertag

Steps to reproduce:

+ In Mobs (Name Tag)

1. Enter or create new world
2. Spawn a mob
3. Get a name tag with custom name
4. Put it to mob

+ In Players (Gamertag)

1. Enter to a multiplayer server (option 1)
2. Enter or create new world and invite a friend (option 2)
3. Look gamertag of players

Expected results:

Player gamertag and mob custon names appears over them

Obtained results:

Player gamertag and mob custom name doesn't appear, only the shadow that rounds name