+ AA6YQ comments below
I experienced two different issues trying downloading QSOs from LoTW.
+ It takes a long time for LoTW to respond with 10K confirmations; you evidently did not wait long enough.
+ Why are you doing a CTRL-"Sync LoTW QSOs"?
+ If you click the LoTW button in the Filter panel at the bottom of the Main window's "Log QSOs" tab, how many QSOs appear in the Log Page Display? These are QSOs that you uploaded to LoTW, but have not been accepted by LoTW.
2. other times, clicking "Sync LotW QSOs" after few seconds a warning window appears saying: "Unable to download from LotW: invalid request"
+ The possibilities are
2. DXKeeper is being prevented from accessing LoTW by an anti-malware application (this would prevent every attempt from succeeding, not just some attempts)
3. Internet connectivity problems between your computer and LoTW