With exactly the correct settings, my WSPR-X running on a Win 7 machine refused to upload spots to the WSPRnet.org database today. When I realised it was not working I did 2 things: (a) I closed the program and restarted it, and (b) reset the PC clock to internet time.
Since doing these things, my "lost" spots successfully uploaded to the database. I have no idea why WSPR-X seems to be so temperamental.Otherwise I like it, especially the realtime,scrolling waterfall and support for WSPR-15, although I have only tried this slower mode once, on LF. Stability needs to be pretty good (over a 15 minute period) for WSPR15.