If this is Google Docs, you should first try disabling any other browser extensions and reloading Google Docs.
If that doesn't help, we still need a Debug ID, and for Google Docs we'd want Debug IDs from both the Zotero Connector and Zotero for reproducing this.
If you don't mind sharing the document with us, you should use File → "Make a copy" and email a share link to support@zotero.org with a link to this thread.
After that, simply deleting the bibliography completely and reinserting it might help.
What word processor? Is this happening before or after you make a selection in the citation dialog?
Can you provide a Debug ID from Zotero for a few minutes of reproducing this?
Its a google document in Google Drive.
If that doesn't help, we still need a Debug ID, and for Google Docs we'd want Debug IDs from both the Zotero Connector and Zotero for reproducing this.
If you don't mind sharing the document with us, you should use File → "Make a copy" and email a share link to support@zotero.org with a link to this thread.
After that, simply deleting the bibliography completely and reinserting it might help.