based on Unity Forum user @Adrenesis' lovely hack for Unity GUI Mask Component movement, more error handling and In-Editor support

LockUIWorldPosition.cs

using System.Collections;
using System.Threading;
using UnityEngine;

[RequireComponent(typeof(RectTransform))]
public class LockUIWorldPosition : MonoBehaviour
{
    private RectTransform rectTransform;
    private Vector3 originalWorldPosition;

    [SerializeField]
    private volatile bool lockInEditor = false;
#if UNITY_EDITOR
    private Coroutine editorUpdate;
#endif

    void Awake()
    {
        LockPosition();
    }

    void LockPosition()
    {
        rectTransform = GetComponent<RectTransform>();
        if (rectTransform == null)
        {
            enabled = false;
            Debug.LogError($"{GetType()} expects {typeof(RectTransform)} to operate properly, disabling", this);
            return;
        }

        originalWorldPosition = rectTransform.position;
    }

    void Update()
    {
        OptionallyFixPosition();
    }

    void OptionallyFixPosition()
    {
        if (rectTransform.position != originalWorldPosition)
        {
            rectTransform.position = originalWorldPosition;
        }
    }

#if UNITY_EDITOR
    IEnumerator UpdateEditor()
    {
        while (lockInEditor)
        {
            OptionallyFixPosition();
            yield return null;
            Thread.Sleep(1);
        }
    }
#endif

    void OnDestroy()
    {

    }

    void OnValidate()
    {
#if UNITY_EDITOR
        if (lockInEditor)
        {
            if (editorUpdate == null)
            {
                LockPosition();
                editorUpdate = StartCoroutine(UpdateEditor());
            }
        }
        else
        {
            if (editorUpdate != null)
            {
                StopCoroutine(editorUpdate);
                editorUpdate = null;
            }
        }
#endif
    }
}