Upon death mobs and players will appear invisible in the nether. I have not had this happen any where else yet, but it started to happen after the minecraft launcher update today. I am constantly having to re-log so I can see mobs again after dying and returning to the nether. Mobs can be heard and can attack, but cannot be seen at all until I re-log. My friend and I are playing on an open LAN if the information helps at all.