This seems to have started with 1.8.9, with the introduction of minecraft realms. Additional LAN players attempting to join a world that is opened to LAN find themselves in an incomplete world; all they see is sky and clouds (what you see before a world is fully created). We tried this with both existing worlds and new worlds, and uninstalled/reinstalled minecraft on both the host and client machines.
Before 1.8.9, multiplayer worked fine.
Is multiplayer being disabled with the introduction of minecraft realms?
Strange. I've used lan mode fine. No multiplayer is not being disabled with the introduction of minecraft realms, it would be social suicide for minecraft.