Clicking on headings in Word's navigation pane does nothing

I've been using Office 2019 (for Windows) until recently, when I upgraded to Office 2021. Since then (not before), I've observed the following behaviour when using Word: while editing a document (any document), at some point left-clicking on headings in the Navigation pane will no longer work to take me there. Right-clicking those headings will still bring up the context menu, but left-clicking doesn't work.

I wasn't able to reproduce this bug exactly. It occurs randomly, meaning some time later, in the same document, left-clicking those headings will work as expected - so it goes in and out.

The problem is temporarily worked around by restarting Word, or by saving the document under a different name (still docx format). However, the problem reoccurs often enough that it is really annoying.

I've not found any helpful threads while searching for previous reports of this problem. Would appreciate any suggestions!

I have not seen this reported before. I am active on a number of forums. Intermittent problems are always tough to troubleshoot.

You can try opening Word in safe mode and seeing if it still happens. It may take a day or so of use to tell. In the meantime, you would be without many customizations you've stored.

You might also want to try a different mouse since this could be a hardware problem.