Downloaded asset bundle prefabs script icons missing in inspector

Question

I have built an AR app with vuforia in Unity. I discovered that the script icons in the inspector of a cloned prefab are missing, whereas the script icons of a drag-and-drop prefab are appearing normally. The model appears normally when the marker is tracked in the drag-and-drop prefab but not in the cloned prefabs. I am not sure is there anything happened to the downloaded cloned prefab?

Downloaded Asset Bundle prefabs

Drag-and-drop prefabs

Error List

AssetManager.cs related to the errors

resumeScene2.cs related to the errors

I tried to rebuild the asset bundle but seems like the script icons were still missing in downloaded prefabs. I think the first four errors have nothing to do with the assetBundle, they are only to checking status of QR scanning whether unlocked or locked.