The bug

While MC-173745 was fixed for the solid inner beam, the outer beams still appear to be affected.

How to reproduce

For beacons, create a setup such that the beam shines through something visually opaque such as a spruce trapdoor.

Expected results

The sides of the beam closest to the player would be visible, such that looking down on the trapdoor would produce a convex figure made of the outer beams just like the inner beams.

Actual results

The sides of the beam closest to the player are not rendered - only the farther sides are. This is inconsistent with the beam on the inside.