Since inserting citations in suggest mode isn't possible, the Zotero menu in google docs is greyed out. However, the keyboard shortcut for insert citations (alt+ctrl+c) still works (tested in Firefox on Windows) and triggers the citation dialog which then produces a broken {Updating} placeholder. It'd be nice if it would, ideally, display an error message or at least just not do anything rather than an action that takes some time and that I need to revert.