When facing a direction between certain yaw values (varies with height, and wider range of invisibility with height), entities (shulkers, for example) become invisible. The video shows a series of shulkers at various y levels above y=256.
I do not know if this is intended, but it seems strange that it should happen.
This a recreation (as suggested by a moderator) of the issue MC-142293, but with me remembering to not use "Optifine".
I have tested it on vanilla, with the same conclusion.