What am I missing? Saving EXR results in a properly sized blank/transparent EXR Image file.

I'm working on loading a picture (JPG, PNG, etc) into the scene, displaying on a plane, and saving it in a different format using a button. In particular, the code for saving images as EXR format, saves an image with the same dimensions, but no pixel values (image is blank). What am I missing here?

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using System.IO;
 
 public class LoadImageOntoTexture : MonoBehaviour
 {
 
     public TextAsset imageAsset;
     int imagewidth;
     int imageheight;
 
     public void Start()
     {
                }
    public void LoadtheImage()
     {
         Texture2D tex = new Texture2D(2, 2);
         tex.LoadImage(imageAsset.bytes);
         GetComponent<Renderer>().material.mainTexture = tex;
         imagewidth = tex.width;
         imageheight = tex.height;
     }

Above code is for loading and displaying an image.

Below code is to save the image as an EXR file to disk.

 public void MakeAEXRFile()
 {     
     Texture2D tex = new Texture2D(imagewidth, imageheight, TextureFormat.RGBAHalf, false,true);
     byte[] bytes = tex.EncodeToEXR(Texture2D.EXRFlags.None);
     File.WriteAllBytes(Application.dataPath + "/../SavedScreenEXR.exr", bytes);
     Object.DestroyImmediate(tex);
 }

I feel as if I'm missing something to set/clarify the pixels or write them to the image before saving... Thanks in advance for your thoughts. Keep on Creating!