I have a large database which has been successfully synchronized with the Zotero server. However, I recently added two Group Libraries to my database, initially with no problem. I then added some more material to one of the group libraries, and when I next tried to sync the main database, I got the conflict resolution panes, indicating that I had 41 conflicts in the database. I worked through those, clicked 'Finish', and received an error message saying that I should do a full reset sync. I did this, only to get the conflict resolution error again, this time with 38 conflicts - all of which had been among the initial 41 conflicts. Again when I came to the end of this, Zotero advised a full reset sync. This I did again, but after about 40 minutes, I got a message saying that there had been an error in the synchronization, and that I would get details by placing the cursor over the red exclamation mark beside the sync button. I clicked OK to indicate I had received this message, since when the sync symbol has kept spinning away, with occasional pauses for one or two seconds, just as if it is performing a synchronization, but the red exclamation mark has not appeared. This has been the situation for almost an hour now.
If I place the cursor on the sync button, I get a message saying 'Sync with Zotero server. Upload accepted - waiting for sync server'.

Is the synchronization working correctly, or is there a problem still? If the latter, how do I stop this false synchronization from continuing indefinitely, and what can I do to restore synchronization between the database on the server and that on the computer? The process I am describing is running on my desktop computer, but I am writing this message on my laptop, in an attempt to avoid crashing Zotero on the desktop, thouhg I fear I might have to do that in order to generate an error report.

Any advice would be most welcome.