When a player is in the water and he passes through blocks, another player cannot see the other player's gamertag when he enters the water as well. It appears that water or blocks interfere with players' gamertags when both are in water.

Step to reproduce the bug:

1. A player must be in the water between blocks as in the video
2. Another player will be able to see the player's Gamertag if he doesn't enter the water too, if the player enters the water he will not be able to see
3. The player will not see the other player's gamertag when they are swimming in the water between blocks