Until i figured out how to add other metadata with Subler, I was first using MetaX to tag and then using Subler to add cnID tag with no problems. I only had the dreaded black screen result if I tried to retag with MetaX after using it once.
How is Subler for pulling in chapter titles? This is one feature I really like in MetaX, but I am still using both it and Subler because MetaX (for Mac) can't do the cnid or HD tags.