I’m trying to make a bunch of objects fade and move to create a UI that moves into place.
when I start my code with the alpha value at 0 and run the code the alpha value returns to 0 but the object is still visible but instead of being white its very transparent but black but if I start the code with alpha set to 1 it becomes completely transparent even when running it multiple times consecutively. I don’t understand why its doing this or how due to the fact that the alpha is 0 at the end and it works when repeating when started with alpha set to 1

I want the object to become opaque and move down at the same time and separately at another point in time move up and become transparent.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.Events;

public class ButtonPress : MonoBehaviour
{
    public string targetTag;
    public UnityEvent<GameObject> OnEnterEvent;
    GameObject uimodel;
    MeshRenderer renderer;
    Material material;

    private void OnTriggerEnter(Collider other)
    {
        if (other.gameObject.tag == targetTag)
        {
            uimodel = GameObject.Find("tester model");
            renderer = uimodel.GetComponent<MeshRenderer>();
            material = renderer.material;
            //StartCoroutine(FadeOut());
            StartCoroutine(FadeIn());
            //OnEnterEvent.Invoke(other.gameObject);
        }
    }
    IEnumerator FadeIn()
    {
        for (float alpha = material.GetFloat("_mask_alpha"); alpha < 1.1f; alpha += 0.1f)
        {
            material.SetFloat("_mask_alpha", alpha);
            yield return new WaitForSeconds(0.001f);
            Vector3 pos = uimodel.transform.position;
            pos.y = (float)(pos.y - 0.01);
            uimodel.transform.position = pos;
        }
        yield return new WaitForSeconds(2f);
        StartCoroutine(FadeOut());
    }

   
    IEnumerator FadeOut()
    {
        for (float alpha = material.GetFloat("_mask_alpha"); alpha > -0.1f; alpha -= 0.1f)
        {
            material.SetFloat("_mask_alpha", alpha);
            yield return new WaitForSeconds(0.001f);
            Vector3 pos = uimodel.transform.position;
            pos.y = (float)(pos.y + 0.01);
            uimodel.transform.position = pos;
        }
    }
}