I'm mining a big open pit underneath our base in the overworld. i'm mining  y - coordinates 8 - 19. i have LVL 4 Beacons set up 100 blocks away from each other in a square in the zone I'm mining with haste 2. They are all set at Y - 27. when mining in the pit the beacons only like to update around 35-40 blocks away from the beacon. If Another player is up top by the beacon it will continue to update closer to the 50 block radius. when we were playing around and making  sure it wasn't glitched or placed improperly we got a popup in the effects window. it said "Effect timer index invalid."