Upload to LOTW fails

[ei9irb]

Uploading of QSO's to LOTW is failing, but without any error messages. After selecting a batch of QSO's to upload (or even a single one) and clicking on the upload button, the 'LOTW end' message appears instantly, indicating that no attempt was made to connect to LOTW. All QSO's have LOTW sent status of 'No' and are there valid to be uploaded. I thought I had a bad QSO record somewhere, and tried uploading some QSO's in small batches, and that worked initially. That seems to validate that my TQSL cert is fine. However, now any valid QSO is not getting updated. I have been using this method of managing my QSO uploads to LOTW for 2 years without any issue. I'm using Log4OM 2.33.0.0. I set logging to 'Trace' and checked the log for any errors, but I'm not seeing anything obvious there. Any help in troubleshooting would be appreciated.

[IW3HMH]

If you have problems with a single QSO it's unlikely you can have a problematic QSO in the archive, as it's not affecting.
have you tried opening TQSL stand alone and check if there are user interface messages coming in?