I believe this is in the 1.13.0 update, from 10/29 of this year.  The problem is that the elytra have a couple problems, both visually and as an in game mechanic.  Both in a singleplayer world and a realms world, even with different skins, the elytra don't appear on the player when equipped.  They still work, as in, flying is still possible, but visually it is as if there is no elytra/chestplate/anything on the player's torso.  Also, when flying without an item in hand, the player's hand disappears and reappears upon landing.  In addition, when a player collides with a wall, the new update has included kinetic energy damage, however, taking this damage also disengages the elytra, which I'm pretty sure is a bug.  Additionally, the elytra have trouble deploying with the use of a Riptide trident.

UPDATE: the problem with the hand disappearing isn't that it entirely disappears, but rather that it moves off of the left side of the screen for some reason.