Camera.ViewportToWorldPoint giving different values

I am having an issue where ViewportToWorldPoint is returning different values in different parts of the code.

The values are correct when code is run in the OnDrawGizmosSelected method:

 void OnDrawGizmosSelected() {
         Vector3 topLeft = GetComponent<Camera>().ViewportToWorldPoint(new Vector3(0, 1, GetComponent<Camera>().nearClipPlane));
         Vector3 topRight = GetComponent<Camera>().ViewportToWorldPoint(new Vector3(1, 1, GetComponent<Camera>().nearClipPlane));
         Vector3 bottomLeft = GetComponent<Camera>().ViewportToWorldPoint(new Vector3(0, 0, GetComponent<Camera>().nearClipPlane));
         Vector3 bottomRight = GetComponent<Camera>().ViewportToWorldPoint(new Vector3(1, 0, GetComponent<Camera>().nearClipPlane));
         Debug.DrawLine (topLeft, target.transform.position, Color.red);
         Debug.DrawLine (topRight, target.transform.position, Color.red);
         Debug.DrawLine (bottomLeft, target.transform.position, Color.red);
         Debug.DrawLine (bottomRight, target.transform.position, Color.red);
         Gizmos.color = Color.yellow;
         Gizmos.DrawSphere(topLeft, 0.1F);
         Gizmos.DrawSphere(topRight, 0.1F);
         Gizmos.DrawSphere(bottomLeft, 0.1F);
         Gizmos.DrawSphere(bottomRight, 0.1F);
 
     }

Yet, when the same (for the most part) code is called in another method in the same script, I get different values:

 void HandleCollision()
     {
         Vector3 pos = transform.position;
         transform.position = _standardPosition;
         Vector3 topLeft = GetComponent<Camera>().ViewportToWorldPoint(new Vector3(0, 1, GetComponent<Camera>().nearClipPlane));
         Vector3 topRight = GetComponent<Camera>().ViewportToWorldPoint(new Vector3(1, 1, GetComponent<Camera>().nearClipPlane));
         Vector3 bottomLeft = GetComponent<Camera>().ViewportToWorldPoint(new Vector3(0, 0, GetComponent<Camera>().nearClipPlane));
         Vector3 bottomRight = GetComponent<Camera>().ViewportToWorldPoint(new Vector3(1, 0, GetComponent<Camera>().nearClipPlane));
         Vector3 center = GetComponent<Camera>().ViewportToWorldPoint(new Vector3(.5f, .5f, GetComponent<Camera>().nearClipPlane));
         transform.position = pos;
         RaycastHit rayhit;
         
         List<RaycastHit> hits = new List<RaycastHit>();
         
         Debug.DrawLine (topLeft, target.transform.position, Color.blue);
         Debug.DrawLine (topRight, target.transform.position, Color.blue);
         Debug.DrawLine (bottomLeft, target.transform.position, Color.blue);
         Debug.DrawLine (bottomRight, target.transform.position, Color.blue);
         Debug.DrawLine (center, target.transform.position, Color.blue);

Here is an image of the issue (red lines are from OnDrawGizmos, blue are from HandleCollision), it seems to be calculating as if the camera is at (0,0,0):

Does anyone know what may be causing the difference? HandleCollision is called during LateUpdate().