Was trying latest windows beta and hadn't installed it yet on this particular PC. I was trying to use the "From Screen" option for reading QR code while I had the 1password account info + QR showing in a web browser.
The signin window just flashed and didn't present an error or fill in the details. Did a screenshot of QR & did From Clipboard which worked though.
1Password Version: 7.4.738
Extension Version: Not Provided
OS Version: Windows 10 (1909)
Sync Type: 1password.com