I donāt know how to reproduce it. But i have met it 2 or 3 times.
Editing document title within the document is OK, but double clicking on document title in the file pane and renaming it sometimes failedāalthough the document title in the file pane was changed indeed.
By the way, document title can be colored or made into heading (format) by shortcuts, but can not be done through menu. itās strange.