End gateway blocks don't render properly when loading a world that already has them, or placing them and then rejoining.

Steps to replicate:

1. Download the world provided below, unzip it, and put it into your saves folder.
2. Join the world. See how there are some invisible end gateways. (Use F3 to see the block name)
3. Step on the pressure plate, or place a block, or interact with the world in almost any way, and most of the end gateways will suddenly become visible. You can also just press F3 + A to reload all chunks.