The 'No pixels' error can mean that the selected layer is empty, but it can also mean that there is an active selection, and no pixels are inside that selection on the selected layer. I don't think a locked layer would result in that error message if you try to use Free Transform. In fact you tend not to get any error message.
If you are certain that there is no user error, and the image still won't play nicely, try selecting all but the BG layer (if it is empty), right click and choose Duplicate layers. Then choose New, and copy them to a new image. I have have several times used this to get out of a messed up image file.