Why are my textures black at runtime?

Just to add extra confusion, I have another Plane, with the same script on it, same set up but that renders fine.

this is the script I am using. The code in flashFunction() works for the stop sign and works fine!

The code in the regular update function effects the blue ring and doesn't work!

 public class trailFader : MonoBehaviour
 {
     public Material myMaterial;
     public float fadeValue;
     public string objectType;
     public GameObject child;
     public bool fadeDir;
     public bool flashIn;
 
     public void Awake()
     {
         objectType = gameObject.tag;
         myMaterial = gameObject.GetComponent<Renderer>().material;
         if (transform.childCount != 0)
         {
             child = transform.GetChild(0).gameObject;
             myMaterial = child.gameObject.GetComponent<Renderer>().material;
         }
     }
 
     public void Update()
     {
         if (objectType == "Untagged")
         {
             var newColor = myMaterial.color;
             newColor.a -= fadeValue;
             myMaterial.color = newColor;
             if (newColor.a < 0)
             {
                 Destroy(gameObject);
             }
 
         }
 
         if (flashIn)
         {
             flashFunction();
         }
 
     }
 
     public void flashFunction()
     {
         if (fadeDir)
         {
             var newColor = myMaterial.color;
             newColor.a += fadeValue*3;
             myMaterial.color = newColor;
             if (newColor.a > 1)
             {
                 fadeDir = !fadeDir;
             }
         }
 
         if (!fadeDir)
         {
             var newColor = myMaterial.color;
             newColor.a -= fadeValue/3;
             myMaterial.color = newColor;
             if (newColor.a < 0)
             {
                 newColor.a = 0;
                 myMaterial.color = newColor;
                 fadeDir = !fadeDir;
                 flashIn = false;
             }
         }
     }
 
     public void OnCollisionEnter(Collision collision)
     {
         if (collision.gameObject.CompareTag("Player"))
         {
             if (objectType == gameObject.tag)
             {
                 flashIn = true;
                 fadeDir = true;
             }
         }
     }
 }