When spreading players in nether, it will teleport the players only to the bedrock layer

The bug

If you spread players in nether they will be teleported(spreaded) only to the bedrock layer.

How to reproduce:

1. Go to nether
2. Write the following command: /spreadplayers ~ ~ 1 2 false @a
   → You will be teleported (or more players if multiplayer) on the bedrock layer