Why isn't Bounds.Encapsulate working as expected?

Based on reading https://docs.unity3d.com/ScriptReference/Bounds.html my expectation is that if I initialize a Bounds with one object's position, then encapsulate a number of additional objects' positions, I'll end up with a bounding box that completely encloses all of the specified objects. To test this, I wrote a quick & dirty script:

         public List<GameObject> objectsToEncapsulate = new List<GameObject>();
 
         private void OnDrawGizmos()
         {
             Gizmos.color = Color.green;
 
             if (objectsToEncapsulate.Count > 0)
             {
                 Bounds newBounds = new Bounds(objectsToEncapsulate[0].transform.position, new Vector3(0,1,0));
                 for (int i = 0; i < objectsToEncapsulate.Count; i++)
                 {
                     newBounds.Encapsulate(objectsToEncapsulate[i].transform.position);
                 }
 
                 Gizmos.DrawWireCube(newBounds.center, newBounds.extents);
             }
         }

This seems to produce weird results when I run it:

The above is a screenshot of the test in action, the only objects in objectsToEncapsulate are the four cubes but instead of the wireframe outline completely encapsulating them, it seems to just be transcribing a smaller internal section of their area- am I just completely misunderstanding how bounds are supposed to behave?