When your camera looks ‘Up’, the beam somehow moves downwards and is invisible to the playerin this case.
Above: You can see the beam above the block. You can see the beam as long as your camera is facing downwards.
Above: When your camera starts looking up, the beam disappears. (It goes inside the block)
This doesn’t occur when the Zindex is set to 0, yet the part collides with it and this happens: