After I have created multiple artboards, and click to rearrange them, I keep getting this phantom artboard that shows up. It doesn't seem to be an actual artboard - I cannot select it with the artboard selection tool, and it doesn't show up on the artboard list, but it's there, being annoying visually, and since I can't select it, I can't figure out how to make it go away. I've tried to close and reopen the file, as well as the program. The only thing that has made it go away is to recreate the artboards in a new file and move the content over.