Missing shadows when using a custom oblique projection matrix

I'm trying to use an oblique top-down perspective, and I ac$$anonymous$$eved t$$anonymous$$s by setting a custom projection matrix script on an orthograp$$anonymous$$c camera:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 [ExecuteInEditMode]
 public class CameraOblique : MonoBehaviour
 { 
     void Start()
     {
         Matrix4x4 mat = Camera.main.projectionMatrix;
         mat[0, 2] = 0.0f;
         mat[1, 2] = 0.1f;
         Camera.main.projectionMatrix = mat;
     }
 }

The perspective comes out how I'm expecting. However, it seems like shadows are being rendered/culled based on whether it would be in the camera's view without the script on.

Pictures with script off:

Pictures with script on:

Notice how the black capsule does not have a shadow in the second picture. It is outside of what was originally viewable by the camera.

Is there any way to fix t$$anonymous$$s so that unity treats everyt$$anonymous$$ng in view of the oblique camera as, well, in view?

Alternatively, a way of doing the top-down oblique perspective w$$anonymous$$ch doesn't change what parts of the floor are visible.