This just happened to me with TT Deluxe 2019. I use Windows 10. Returns would not transmit. It kept saying it needed an update, but checking for updates said TT was already updated. Researching online brought up the suggestion to do a manual TT update for Windows. I searched, downloaded and installed the update and my returns finally transmitted. Give it a try.
P.S. I did not uninstall/reinstall TT. I just downloaded and installed the update.
P.P.S. Illinois return also submitted successfully.
