Google Docs integration intermittently fails after first citation — Zotero 9.0.6

syazafilzah

I'm using Zotero 9.0.6 with Zotero Connector 5.0.215 on Windows/Chrome.
After updating Zotero, Google Docs citation integration became unreliable.
Typical sequence:
1. Open Google Docs with Zotero desktop running.
2. Add/Edit Citation works successfully for the first citation.
3. When I try to insert another citation, Zotero reports: “Zotero experienced an error updating your document.”
4. Sometimes subsequent attempts produce: “A word processor integration command is already running.”
5. Restarting Zotero/refreshing Google Docs temporarily fixes it, but the problem returns.
The same problem has occurred in a completely new blank Google Doc, so it does not appear to be specific to my existing document.
Zotero Connector Debug ID captured while reproducing the problem:
D1313239378
The problem is intermittent. At one point citation insertion started working normally again, but later the same error returned.