I have a large document (352 pages) and a block of text over several pages suddenly appeared with a reddish-orange colour overlaid on text, but not objects. There's a border as well in a darker colour. Not all the pages are the same tint -- even facing pages seem to have different tints. The colour doesn't appear in an exported PDF, nor in Preview, Bleeds, or Slugs.
I've tried every imaginable check box, but no joy! Any ideas about how to get rid?