Lerp being performed instantly, rather than gradually

Ive been working on a project within Unity where im making a UFO cow abduction game. I have been researching Raycasthit and trying to combine this with a Vector.Lerp so that when the UFO is directly above a cow prefab it should gradually suck it up. The issue im experiencing is that when am directly over a cow prefab it gets sucked up instantly rather than gradually.

This is the exact same behaviour as when i was using a new Vector 3 for the raycastHit.tranform.position. Please see my TractorBeam class below:

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

public class TractorBeam : MonoBehaviour
{
// Start is called before the first frame update
private bool tractorBeamEnabled = false;
public GameObject tractorBeam;


public void StopTractorBeam(bool death)
{
    if (death)
    {
        Destroy(GameObject.FindWithTag("TractorBeam"));
    }
}
void Start()
{
    
}



// Update is called once per frame
void Update()
{
    // Tractor beam
    tractorBeam.GetComponent<Renderer>().enabled = false;
    if (Input.GetKey("space"))
    {

        tractorBeamEnabled = true;
        tractorBeam.GetComponent<Renderer>().enabled = true;
        RaycastHit raycastHit;
        if (Physics.Raycast(transform.position, Vector3.down, out raycastHit, Mathf.Infinity))
            if (raycastHit.collider.tag != "Jet" && raycastHit.collider.tag == "Cow1" || raycastHit.collider.tag == "Cow2")
            {
                Debug.Log("Cow abducted!");
                float startTime = Time.time;
                float speed = 1f;
                Transform endPos = raycastHit.transform;
                Transform startPos = gameObject.transform;
                float journeyLength = Vector3.Distance(startPos.position, endPos.position);
                float distCovered = (Time.time - startTime * speed);
                float fractionOfJourney = distCovered / journeyLength;
                raycastHit.collider.transform.position = Vector3.Lerp(startPos.position, endPos.position, fractionOfJourney);
                
                //raycastHit.transform.position = new Vector3(raycastHit.transform.position.x, gameObject.transform.position.y - raycastHit.transform.position.y, raycastHit.transform.position.z);
                FindObjectOfType<GameManager>().PointManager(1);
            }


    }
}
}

After looking at a bunch of articles ive been trying to calculate the fractionOfJourney so that it is a gradual movement to the UFO, as well as changing the float speed variable but regardless of what i do it seems to just be instant. I did have it before where my UFO was instantly lerping to the cow, and then tracking it whilst i held space but i have since made changes and cant figure out what i was doing then - but im pretty sure that was close (but again it was still just moving instantly so probably not as close as i thought).

Im still new to unity and really enjoying learning it so forgive me if my code is awful! Any help or tips would be really appreciated and thank you for your time.

Vector3.Lerp interpolates between the two given positions and a given factor between 0 and 1.

Your

float distCovered = (Time.time - startTime * speed);

basically equals

Time.time - Time.time * speed // since startTime = Time.time
Time.time - Time.time * 1 // since speed = 1f
= 0

=> You always instant return

gameObject.transform.position

In general if you just want to linear move towards the desired position you could use Vector3.MoveTowards instead which as said moves towards the target with a fixed velocity

raycastHit.transform.position = Vector3.MoveTowards(raycastHit.transform.position, transform.position, speed * Time.deltaTime);

Note the multiplication by Time.deltaTime which converts your value from a speed per frame into a frame rate independent speed per second.

You could even split the Y movement from the XZ movement in order to "suck" the object faster to the center of the beam than upwards - preventing a diagonal movement of the objects

Something like e.g.

var step = speed * Time.deltaTime;
var hitPos = raycastHit.transform.position;
var targetPos = transform.poaition;
var targetPosXZ = targetPos;
targetPosXZ.y = hitPos.y;
var newPos = Vector3.MoveTowards(hitPos, targetPosXZ, step * 3);
newPos.y = Mathf.MoveTowards(hitPos.y, targetPos.y, step);

raycastHit.transform.position = newPos;

Which would cause the object to move towards the beam center 3 times the velocity than upwards, which you can adjust accordingly.

Then further you could also include a check for

if(raycastHit.transform.position ==  transform.position)
{
    Destroy(raycastHit.transform.gameObject);
    FindObjectOfType<GameManager>().PointManager(1);
}

You might be interested in rather using a Physics.SphereCast instead in order to cover a certain radius and not only a single ray - according to your beam visuals