When opening spectator mode and using the f5 view water and a random amount of each entity apears to be non existent when placed behind the head of this gamemode.
I also checked Issue MC-198457 where the end crystals dont render behind stained glass, this one can getfixed with "fabulous graphics" but when put on fancy wich is what most players use there is a random chance that a entity will be invisible or not, when the graphics are put on fast this chance increases but still some apear as visible and others as invisible. Also noticed that in fancy graphics water can be seen only at a certain angle of view, remember that this whole issue is in spectator mode in f5 mode.