Bug: false player culling on nether roof after dimension change when using world threader mod

[runningbird2]

Summary

Players can be falsely culled after travelling through portals when using the worldthreader mod.

Affected Scenarios

• Portal transfer: visibility can desync immediately after dimension change.
• Command teleport: /tp can cause temporary incorrect culling.

Steps To Reproduce

1. Put two players on the nether roof at close range with line of sight.
2. Move one player through a nether portal or use /tp for a large position jump.
3. Observe that one player can become invisible to the other despite expected visibility.

Expected

Players that are in direct line of sight should remain visible after portal transitions and teleport jumps.

Actual

Players can be marked hidden for a short period or remain hidden until later state changes.