Log4OM

I am trying out the automatic upload of QSOs. Automatic uploads to EQSL and QRZCOM work fine. However, LOTW does not. When I close Log4OM (v. 2.27.1.0), three messages appear:
Uploading LOTW data (120 second timeout)
Saving form status
Closing down Log4OM application.

And then it sits there forever. The QSOs do not upload, and a background log4om process remains running. I have to close it with Task Manager to restart Log4OM.

I am a LOTW user. My password and TQSL setup should be correct, because I've been manually uploading the contacts for several years, and that has always worked. When I unchecked the box for auto-upload to LOTW on program exit, the problem disappeared.

Does this have something to do with the matching the Confirmations settings with the External Services settings for LOTW? I've never quite understood the nuances of the various categories of Sent and Received. I just left those external service settings alone, and things worked up until now.

I think I figured this one out myself. It was difficult to find because "LOTW" and "upload" are common words that the forum's software refuses to search on. "External services" led to an answer, in this thread:
https://forum.log4om.com/viewtopic.php?p=43065

The answer, from G4POP (thanks, Terry!) is: "Enable TQSL Interactive mode." This is in Settings, "External Services" page, LOTW tab.

Apparently, what happened was that a number of paper QSL cards from years ago were granted in LOTW due to my initial DXCC application, but I'd never gone through and tagged them as such in Log4OM. So during my first automatic uploads, LOTW rejected them en masse, causing Log4OM to hang on exit. When I enabled TQSL Interactive Mode, TQSL again rejected them, but now I could see what was wrong, told TQSL to keep going, and all was well. As a bonus, now Log4OM now assumed that these old QSOs were handled. So now I can run without TQSL interactive mode, and things work as the should.