Can't save changes to Keynote Presentation
I've used Keynote for years, but suddenly can't save updates to a presentation. I get this error message: "Couldn't auto-save document. Your most recent changes might be lost." I've tried reducing the size of the presentation. Saving it to a documents folder. It's frustrating as I'd like to add presenter notes.
Help!
MacBook Pro 13″, OS X 10.11