Duplicate of #611. Plummet told me a new report was warranted as the old one had a misleading title.

Beholders do not function on multiplayer when the player is more than 80 blocks away. Using a bound occult gem will display the subtitle but the players vision will not adjust. Eye Spy advancement is still given correctly. I tested this with a blank server running just AC to ensure its not a mod compat issue. I believe it has something to do with entity rendering. IIRC the default distance at which entities stop rendering is 80 blocks.