When enabling cinematic camera mode in a single player world, move your head around and then pause the game. Your head will pause in it's last position but doing this in a multiplayer server or realm server, this will cause your player's head to stop moving but it should not because it is a multiplayer world. The player's head should keep moving.
How to reproduce
1. Go into a realm or multiplayer server.
2. Enable cinematic camera mode
3. Move your player's head around really fast.
4. Pause the game.
Is this still an issue in the most recent versions (currently that is 1.12.2, or the latest 1.13 development snapshot 18w07c) of Minecraft?