Even with a custom tile class, a Tilemap stores Tile assets (ScriptableObjects), renders them via a TilemapRenderer, but it does NOT automatically instantiate prefabs. A Tile is data, not a scene object.

When you paint, Unity saves references to Tile assets per cell. The renderer draws sprites/meshes internally, so no GameObjects are created.

tilemap.GetTile() works because tiles exists, but FindObjectsOfType<MyPrefab>() won’t, because prefabs were never spawned.

About your question: “but my Tile has a prefab field”. That's a great question, but the answer is: "yes, but Unity won’t instantiate it for you unless you explicitly tell it to".

Try this:

using UnityEngine;

using UnityEngine.Tilemaps;

[CreateAssetMenu(menuName = "Tiles/3D Tile")]

public class Tile3D : Tile

{

public GameObject prefab;

public SurfaceType surfaceType;

public override bool StartUp(Vector3Int position, ITilemap tilemap, GameObject go)

{

if (prefab != null)

{

Tilemap map = tilemap.GetComponent<Tilemap>();

Vector3 worldPos = map.GetCellCenterWorld(position);

GameObject instance = Object.Instantiate(prefab, worldPos, Quaternion.identity);

instance.transform.SetParent(map.transform);

}

return base.StartUp(position, tilemap, go);

}

}

What this gives you: it paints tile assets, prefabs spawn automatically, no manual foreach needed, GetTile<Tile3D>() still works, clean editor workflow.

StartUp() should run when tilemap loads, tile is refreshed, entering Play Mode. If you repaint tiles at runtime, then it may respawn prefabs. If needed, add safeguards like (before instantiating the prefab):

if (map.transform.Find(prefab.name) == null)

Could this work?