Screen Control Inspector, in the Layout mode the screen is empty but there is stil a Control Panel in the inspector visible.

The problem definitely seems to be around this Keyboard1.

Have you tried exporting your full layout and importing it to a truly blank canvas?

I made a blank by starting with the minimalist keyboard template and deleting everything I could. See attached.

After selecting CMD+A, can you not just hit backspace to delete any remaining items?

I'm not sure I am understanding the issue. Is it possible the problem panel is part of a group? Maybe try selecting all and then ungroup?

I don't understand the entry that has "Notes Keyboard1" etc. If I make a blank concert, I do not see that. Everything else looks as you have shown. Will it allow you to delete that line?

Have you changed the aspect ratio of the canvas? I wonder if there is an object outside the current frame?

Sorry, I can't think of anything else to try.

You may need to export your patches and rebuild the canvas?

You are welcome; I hope you will find a solution.