I was just experimenting with something and I found that when an entity has the "glowing" effect on it, and when the glowing effect ends, it seems to un-render transparent blocks, the item held in the player's hand, as well as the ocean it would seem. This glitch (I manage to capture it in the second image here) lasts only for about one frame and it happens just as an entity loses their glowing effect. (I tested it on a chicken)

The command I used to give the glowing effect was this:
/effect @e[type=Chicken,c=1] minecraft:glowing 1 0