I generated this world in Minecraft 18w49a using the Amplified setting and used the seed "Pomme de terre." and after a while of flying around the spawn, the chunks stopped loading. I tried F3 + A, didn't work, and I tried placing and breaking blocks in the unloaded area, didn't work. Even more unusual, there was random floating liquid in the unloaded area.

It wasn't block-updating either.