sprite(missing) at runtime

I have a prefab that I am spawning in my 2D game. In the editor environment everything looks fine but at runtime the sprite field in the inspector says:

sprite(missing)

They are not just hidden, at edit time the sprite has a reference and at runtime the reference is broken. Has anyone else had this problem?

Posts about similar problems often mention the sorting layer or order but that's not the issue because I can actually see that the reference is broken in the inspector at runtime.

I have also seen some that mention script order but I have not customized that.....those posts didn't really explain enough for me to understand what they were talking about.

I have also read a post that mentions explicitly loading the asset but that made no difference.

Please help!