Players riding horses in Local Lan network are invisible

Me and my brother playing Minecraft together via the option "Open to Lan" found horses. After taming one of them I went mining. After me returning to the surface and my brother having tamed another horse he was riding, I wasn't able to see him shooting arrows at me.

After he dismounted I could see him. Again he climbed on the horse, I was able to see him.

please fix this bug, Mojang, it's horrible for PvP.

(sorry for my english, I'm a german student)