On a LAN world, after the players teleport, they become invisible to each other.

Steps to reproduce:

1) Constantly teleport all players into unloaded chunks.
2) After doing this a few times, both players become invisible to each other.

To fix:
The only way to fix the issue is by killing both players. After doing this, they become visible to each other. Switching game modes and using potions of invisibility does not resolve the issue.