I had the same problem but was able to work around it. The key was to not do this through the sidebar. When connecting to flow on the phone you get to the point where you have to scaqn a QR code. The QR-code is not the same QR code as in the sidebar on desktop. Instead enter opera.com/connect in a new tab on the desktop. There is a QR code which is compatible with your phone setup. After scanning this QR code it should show the same 6 digits as on the phone. Acknowledge on the desktop tab they are the same