I am still having this issue (as of 5.0.180) - and I can confirm that it is not triggered by any particular edit. Going back to a version that I know had working references does not fix it (the issue appears in the old version now as well).

Win 11/Zotero 7.0.20 64-bit / Connector 5.0.180 / Chrome 139.0.7258.127

Clicking the "Z" button in the toolbar does nothing if I am hovering over an existing citation (silently fails). If it is not hovering over an existing citation it works normally. It appears that the document is still fully linked, as I can use the "Refresh" function and add new citations in new places as per normal, but if I do, they immediately lose the "Add/Edit citation hover button and get replaced with simple the zotero link for that citation. The bibliography appears to be unaffected, except that I cannot edit existing citations, and newly added ones immediately break the "edit" functionality as soon as they are added.

If I go into the logs, I do see the Error 500 notification - but it does not appear at any point as a popup error message, only in the logs.

@adomasven

D751060100
1343809137

I believe the second number above is that: 1343809137

There doesn't seem to be anything fundamentally wrong in these logs. You should see Troubleshooting Errors in Word Processor Documents.

Did you try disabling other browser extensions, or trying in Firefox?

Does it work with a different Google account?

@adomasven does that assist with debugging? It is possible, though not ideal, to use another google account temporarily, but there is no guarantee that the same problem does not recur on the new one.