KDE Neon distro.
1. Create new connection with key.
2. Browsing 'Root path' (can browse remote filesystem) and 'Test SFTP connection' also works
3. When I confirm the setup, Remote Host list shows error 'Could not connect to SFTP server to 'xxxxxxxxx'.
4. Editing the connection 'user name' is blank (not remembered).
Log file is in second comment (found out how to edit comments)