Floating Lava/Water That's Not Even There

As I was flying around over an ocean in the 1.14 snapshot, blocks (as shown in the attachments w/ two pictures and a video) would pop up in front of me, floating in the air. At first I thought that there might've been a mountain in front of me that hadn't loaded in. But in less than 5 seconds, the floating lava/water blocks would disappear and there would be only air.