Creating bookmarks from Word headings getting extra numbering added ("0B, 9B)"

I normally use Acrobat XI Pro to convert complex Word 2013 training documents to pdf. I add bookmarks using the headings in the Word document. It had been working fine, but all of a sudden I started getting extra characters automatically added to my bookmarks, (like numbering at the beginning of each bookmark, "0B, 9B, etc." Of course, it looks awful and I can't publish this way. How do I fix this?