I am having a problem with Zotero citations in Microsoft Word.

When I insert a citation using Zotero's Add/Edit Citation, Zotero does not insert the formatted citation. Instead, the text "citation" appears in the document.

I have tested this in a completely new blank Word document, so the problem is not limited to my dissertation.

What I have confirmed:

Zotero version: 9.0.6 (64-bit)
Zotero has the correct bibliographic information. For example, Zotero can generate the bibliography entry for Mubiru and Banda (2012) correctly.
Microsoft Word's normal fields work correctly. I tested a DATE field and Word updated it successfully.
The Microsoft Word Add-in is installed.
I have already reinstalled the Microsoft Word Add-in, but the problem remains.
When I press Alt+F9 on the Zotero citation field, I see { ADDIN ZOTERO_TEMP }.
Zotero Refresh does not convert the temporary field into the actual citation.
The problem occurs even in a new blank Word document.

Example:

I type:

Test

Then I use Zotero → Add/Edit Citation and select:

Mubiru, J., & Banda, E. (2012). Monthly average daily global solar irradiation maps for Uganda: A location in the equatorial region. Renewable Energy, 41, 412–415.

Instead of producing something like:

Test (Mubiru & Banda, 2012)

it produces:

Test citation

I have also generated a Zotero Debug Output ID:

D419382951

Could someone please help identify why the Zotero Word integration is leaving the field as ZOTERO_TEMP instead of completing the citation?

Thank you.