I had set up a Minecraft 1.8.8 server and play together with a friend on this server. All clients and the server are Vanilla, no mods installed.
I had created Map#6 some time ago, and I copied it for my friend. It worked for some time that we both could see each other.
A few days ago, this feature broke. I can't see my friend on my map. But he can see me. The maps are identical, both Map#6.
How can I solve this?