After the most recent Acrobat DC update, we suddenly could not paste any text into the alt text field or the title, subject, author, and keyword fields in document properties. The cursor was there, but nothing appeared when we tried to paste. This happened when copying from any application (Word, PowerPoint, even from within the PDF itself). Oddly, we could paste into the body of the PDF, just not the alt text and document property fields. Ultimately we had to uninstall and reinstall, which seemed to fix the problem. But we have no idea what caused this malfunction in the first place. It happened with four different PC users but not with Mac users.