Nether floor is water

In multiplayer, when you activate the nether reactor on ice, the second person will have water as the floor instead of obsidian.

What I expected to happen was...:

The second person's floor would be the same as the first's.

What actually happened was...:
I was the host and my floor was obsidian and I looked at the second person's screen and their floor was made of water.

Steps to Reproduce:
1. Host a multiplayer game in survival.
2. Build and activate the nether reactor with a friend.
3. Have the friend quit and then join again.
4. Your friend should see water as the floor of the nether instead of obsidian.