if you place a beacon on blocks that activate the beam, then go far enough away to unload the chunk, then go back to the area and destroy the beacon, then the beams stay loaded. Logging in and logging out clears the beams.
Tested in single player creative mode.
MC-65559
Beacon Beam Remains
Resolved
Duplicate
1
Clint Kennedy
(Unassigned)
Unconfirmed
Minecraft 14w32a
Retrieved
Experience this as well. I believe is because MC-62166. Relogging into the world, fixes it. If F3 + A works, then it's a duplicate.