When you see the beam from the same elevation of the beacon you can look as up as the player can and you can seet he beam without problems, but if you fly up and get higher you cans see that the beam desapears, so you have to look down to be able to see the beam. the higher you are, the more down you have to look to see the beam. The up and down angle is independent from beacon to beacon, so if you put a beacon higher you can´t see the beam of the lower but see the beam of the higher, until you reach some altitude and then you´ll be unable to see any of the beams, maybe something related with rendering the beacon?

can´t tell if this happens also with 14w34a/b/c at this momment because my launcher doesn´t show those options for some reason (another bug maybe? lets look at mc launcher bugs, don´t know if is already there that)

Anyway tested in 14w33c and there is no bug