Linecast blocked by colliders not actually in the way?

I'm having trouble with a Linecast that goes from a "sun" object to all the cubes on a board. The Linecast appears to be getting interrupted by cubes that are not in the way of what should be a straight line from the center of one transform.position to another.

Here's an example of what I'm talking about:

In the above pic, if I remove the cube I've circled, the Linecast hits the target I've pointed to. All of these objects are on the same Z, so that's not the problem.

Here's an example of their Vector3s here:

• linecast origin: 0.5f, 0.1f, 0f

• target: 0.4f, -0.6f, 0f

• blocking: 0.3f, 0.1f, 0f

I'm really baffled. The blocker is actually further to the left than the target. What is happening to the Linecast here?

Just for completion's sake, here's the snippet of relevant code:

      foreach (SideDigScript d in allCubes) {
         Vector3 blockPos = d.transform.position;
         
         if (Physics.Linecast (theSun.position, blockPos, out hitInfo)) {
             if (hitInfo.collider.gameObject.GetComponent<SideDigScript>() == d) {

// bla blah