Can't copy and paste into Bookmarks and Properties

I'm finding I am having a similar issue. I use Adobe Acrobat DC for many different things. One of the things I do on a routine basis is prepare documents for publication. I have not changed my processes in any way, others will draft documents in Microsoft Word, which I proof the formatting and then convert to PDF (I usually use Save As and then change the file type to PDF making sure Create bookmarks using>Headings is selected). Quite standard now for the past 8 years. I then also create covers for the documents using InDesign which I then export as a high quality print to PDF. Once these are PDF's, I then merge the 2 documents together in DC, sorting bookmarks and adding the title of the document and author to the properties. Usually to sort this, I copy the title and author from the text within the document and paste into the properties. This is no longer working for me. It will let me select the text, and copy the text (it shows up in my clipboard and I can paste elsewhere), but I can't paste into anything in the document (bookmarks, properties etc...).