you will get the error message "Could not make a new layer from the selection because the selected area is empty." All these errors are a result of photoshop not identifying pixels that you are trying to cut/copy.
I would say they are the result of the active Layer not being a pixel layer or being empty in the selected region, judging from the remedy you describe.
And what you seem to call »box« goes by the name of »Panel«.
I would agree with your post c.pfaffenbichler - "Panel" - knew it was something other than box - I am a total amateur so finding this simple solution where no one could figure it out elsewhere seemed worth posting since it took all morning to figure it out.
Placing a picture in a layer - you would think creates a pixel layer - but apparently that is not always the case.
Pasting or Placing pixel content creates a new Layer.
You might want to check out the Move Tool’s Auto-Select if you want to quickly select a Layer by clicking on its content or ctrl-clicking with the Move Tool to get a list of Layers which have content at that spot.
Are you aware of the Edit - Copy Merged function?
Convert it to a smart object and rasterize it again, that worked for me.