iTunes "Sign in" does nothing

I recently used PC Mover to move my old PC to a new Dell. Now, I can't sign into iTunes. When I click "Account", then "Authorize this computer", then "Sign in", nothing happens: no pop-up window, no error message, just nothing. I've updated iTunes, uninstalled it, re-downloaded it, and reinstalled it. I've run it as administrator and in safe mode. I'm running the updated Windows 10 and I haven't installed any conflicting programs. iTunes is not being blocked by Windows Firewall and I don't have Norton or any anti-virus software other than what came with Windows and was on my previous HP desktop. I've never had this issue until using this Dell PC. I've spent a significant amount of time in chat and on the phone with Apple Support with no resolution. If anyone has any experience with this issue, suggestions would be much appreciated.