Bookmarks suddenly unable to be renamed

[Eric5C87]

Working with a document created using Adobe Acrobat Standard DC, Continuous Release Version 2020.013.20074.

After creating, naming and editing numerous bookmarks, I am suddenly unable to rename them- upon creation of the new bookmark, the text bar where one would enter the title is highlighted black, and pressing any key creates a chime from Windows.  Selecting a previously-created bookmark and pressing F2 has the same result- no way to edit/change the title of the bookmark.

[Eric5C87]

Completely closing Adobe & restarting the computer seems to have resolved the issue.  Still uncertain as to why it began happening in the first place.