Zotero 7. beta.64's "Add/edit citation" for Microsoft Word is invalid. The Quick Format citation appears in the taskbar, but it doesn't respond when clicked.
OK, so disable all your plugins, and then re-enable them until you find the one that's breaking this. Then let us know and report it to the plugin developer.
https://s3.amazonaws.com/zotero.org/images/forums/u8894157/dp3dvlqdohv2qyaon4h2.jpg