Endermen do a weird half-teleport any time they take damage, where they warp somewhere for a microsecond, and then instantly return back to the same location where they took damage at.
How to reproduce:
Make the enderman take damage by any means (other than water): punching, cactuses, magma block, campfire, iron golems, falling anvil, fall damage, etc.
Best tested in night time, as they don't do the random teleportation they do at daytime.
The bug is gone. Looks like this was just a MC-101700 duplicate